Siga este link para ver outros tipos de publicações sobre o tema: Follicles.
Artigos de revistas sobre o tema "Follicles"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Veja os 50 melhores artigos de revistas para estudos sobre o assunto "Follicles".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Veja os artigos de revistas das mais diversas áreas científicas e compile uma bibliografia correta.
1
Ryan, K. E., S. M. Casey, M. J. Canty, M. A. Crowe, F. Martin e A. C. O. Evans. "Akt and Erk signal transduction pathways are early markers of differentiation in dominant and subordinate ovarian follicles in cattle". Reproduction 133, n.º 3 (março de 2007): 617–26. http://dx.doi.org/10.1530/rep-06-0130.
Texto completo da fonteResumo:
Dominant follicles are those that continue to develop and have the potential to ovulate while subordinate follicles regress. Characteristics of dominant follicles include a larger diameter, higher intrafollicular estradiol, and lower IGF-binding protein (IGFBP)-4 concentrations compared with other cohort follicles. Follicle development is regulated by endocrine hormones that act via intracellular signaling pathways. Here, we show the differences in Akt, Erk, c-Jun N-terminal protein kinase, and p-38 signaling pathways between dominant and subordinate follicles at the dominance stage of the follicle wave. However, earlier in the follicle wave (dominant follicle selection), there were only differences in the levels of Akt and Erk signal transduction proteins among dominant and subordinate follicles. Using this profile of Akt and Erk protein expression in granulosa and theca cells of selected dominant follicles compared with subordinate follicles, we suggest a predictive model to identify future dominant and subordinate follicles from the pool of otherwise similar cohort follicles at the time of follicle wave emergence. We conclude that the Erk and Akt signal transduction pathways are important for dominant follicle selection and development and, furthermore, that the observed differences in these pathways mark the future dominant follicle from subordinate follicles before differences in follicular diameter, follicular fluid estradiol, and IGFBP-4 concentrations are apparent.
2
Greenfield, L. J., J. T. Hackett e J. Linden. "Xenopus oocyte K+ current. II. Adenylyl cyclase-linked receptors on follicle cells". American Journal of Physiology-Cell Physiology 259, n.º 5 (1 de novembro de 1990): C784—C791. http://dx.doi.org/10.1152/ajpcell.1990.259.5.c784.
Texto completo da fonteResumo:
Xenopus ovarian follicles consist of single large oocytes surrounded by a layer of small follicle cells that are coupled to the oocyte by gap junctions. Hyperpolarizing K+ currents can be detected in the oocytes of follicles stimulated with adenosine, isoproterenol, follicle-stimulating hormone (FSH), or microinjected adenosine 3',5'-cyclic monophosphate (cAMP). We show that cAMP accumulation can be detected in follicles incubated with the adenosine agonist 5'-N-ethylcarboxamidoadenosine (NECA), isoproterenol, or FSH, but only if forskolin and a phosphodiesterase inhibitor are also added. Treatment of follicles with collagenase has been reported to reduce, but usually not to eliminate, cAMP-activated K+ currents. In this study we show that collagenase treatment alone does not completely remove follicle cells or receptor-mediated cAMP accumulation measured in follicles. cAMP accumulation and cAMP-dependent K+ currents are both eliminated when the follicle cells are completely removed by a technique involving treatment of follicles with collagenase and hypertonic saline. Oocytes completely stripped of follicle cells fail to accumulate cAMP in response to receptor agonists and forskolin. Isolated follicle cells derived from single follicles (but without the oocyte present) accumulate cAMP in response to these drugs to an extent equivalent to the response seen in single intact follicles. Adenylyl cyclase-linked receptors of Xenopus follicles thus appear to be located exclusively on follicle cells. The data suggest that cAMP-dependent K+ currents, although measured in oocytes, may be generated in follicle cells which communicate with oocytes. Another possibility is that a high resting K+ conductance in follicle cells is communicated to oocytes via cAMP-sensitive gap junctions.
3
Hatzirodos, N., H. F. Irving-Rodgers e R. J. Rodgers. "333. HETEROGENEITY OF GENE EXPRESSION IN BOVINE SMALL FOLLICLES". Reproduction, Fertility and Development 22, n.º 9 (2010): 133. http://dx.doi.org/10.1071/srb10abs333.
Texto completo da fonteResumo:
Small antral follicles <5 mm in bovine ovaries undergo one of two fates: further growth and selection to become the dominant follicle for ovulation, or atresia. Atresia can occur before, during or after selection. As follicle grow past >5 mm there is upregulation in expression of focimatrix genes and later upregulation of the LH receptor and steroidogenic enzymes, especially aromatase, in the granulosa cells. For follicles at sizes >5 mm entering atresia the granulosa cells are the first in the follicle to die. Thus expression of genes in granulosa cells is critical to the fate of the follicle. To examine granulosa cells of small follicles we collected bovine ovaries and dissected follicles, removed part of the follicle wall for subsequent classification of health or atresia, and harvested the remaining granulosa cells for RNA isolation. Follicles examined included small follicles (<5 mm), both healthy (n = 10) and atretic (n =5), and healthy large follicles (>10 mm, n = 4). RNA was hybridized to Affymetrix GeneChip Bovine Genome Arrays and the results were analysed using Partek Genomics Suite software. The number of genes which were 2 fold differentially regulated between large and small follicles by Benjamini Hochberg post hoc test (False Discovery Rate, P < 0.05) was 2408 and between healthy and atretic small follicles was 4931. The coefficient of variation (CV; SD/mean × 100) for the expression level of each gene for each group was calculated. A gene frequency distribution indicated greater heterogeneity in expression levels in small follicles in comparison to large follicles. Furthermore, the greatest variability in genes in small follicles includes those that are either up or down regulated due to atresia or growth. We therefore conclude that variability in small follicles is a consequence of alternative fates that small follicle can undergo.
4
Hornick, J. E., F. E. Duncan, L. D. Shea e T. K. Woodruff. "Multiple follicle culture supports primary follicle growth through paracrine-acting signals". REPRODUCTION 145, n.º 1 (janeiro de 2013): 19–32. http://dx.doi.org/10.1530/rep-12-0233.
Texto completo da fonteResumo:
In vitro follicle growth in alginate hydrogels is a unique and versatile method for studying ovarian and follicle biology that may also have implications for fertility preservation. Current culture systems support the development of isolated mouse follicles from the secondary stage onward. However, it has been a challenge to grow smaller follicles in vitro due to the dissociation of the oocyte from companion somatic cells. Recent work has demonstrated that coculturing primary follicles with mouse embryonic fibroblasts or ovarian stromal cells supports follicle survival and growth. In this study, we demonstrate that follicles themselves can exert a beneficial coculture effect. When primary follicles were cultured in groups of five or ten (multiple follicle culture), there was increased growth and survival. The multiple follicle culture approach maintained follicle integrity and resulted in the formation of antral stage follicles containing meiotically competent gametes. The growth and survival of primary follicles were highly number dependent, with the most significant enhancement observed when the largest number of follicles was grown together. Our data suggest that the follicle unit is necessary to produce the secreted factors responsible for the supportive effects of multiple follicle culture, as neither denuded oocytes, oocyte-secreted factors, nor granulosa cells alone were sufficient to support early follicle growth in vitro. Therefore, there may be signaling from both the oocyte and the follicle that enhances growth but requires both components in a feedback mechanism. This work is consistent with current in vivo models for follicle growth and thus advances the movement to recapitulate the ovarian environment in vitro.
5
Nagashima, Jennifer B., Andrea M. Hill e Nucharin Songsasen. "In vitro development of mechanically and enzymatically isolated cat ovarian follicles". Reproduction and Fertility 2, n.º 1 (23 de março de 2021): 35–46. http://dx.doi.org/10.1530/raf-20-0067.
Texto completo da fonteResumo:
Graphical Abstract Isolation of ovarian follicles is a key step in culture systems for large mammalian species to promote the continued growth of follicles beyond the preantral stage in fertility preservation efforts. Still, mechanical isolation methods are user-skill dependent and time-consuming, whereas enzymatic strategies carry increased risk of damaging theca cell layers and the basement membranes. Here, we sought to determine an optimal method to rescue domestic cat (Felis catus) early antral and antral stage follicles from ovarian tissue and to evaluate the influence of isolation strategy on follicle development, survival, and gene expression during 14 days of in vitro culture in alginate hydrogel. Mechanical isolation was compared with 90 min digestion in 0.7 and 1.4 Wünsch units/mL Liberase blendzyme (0.7L and 1.4L, respectively). Mechanical isolation resulted in improved follicle growth and survival, and better antral cavity and theca cell maintenance in vitro, compared with 1.4L (P < 0.05) but displayed higher levels of apoptosis after incubation compared with enzymatically isolated follicles. However, differences in follicle growth and survival were not apparent until 7+ days in vitro. Expressions of CYP19A1, GDF9, LHR, or VEGFA were similar among isolation-strategies. Cultured follicles from all isolation methods displayed reduced STAR expression compared with freshly isolated follicles obtained mechanically or via 0.7L, suggesting that prolonged culture resulted in loss of theca cell presence and/or function. In sum, early antral and antral stage follicle development in vitro is significantly influenced by isolation strategy but not necessarily observable in the absence of extended culture. These results indicate that additional care must be taken in follicle isolation optimizations for genome rescue and fertility preservation efforts. Lay summary The ovary contains hundreds of eggs with only a select few developing from an immature stage through to ovulation over the course of an animal's lifetime. Rescue of eggs from this pool, and the ability to grow them in culture to a mature stage, would be incredibly valuable for fertility preservation efforts in both humans and endangered species. Currently, the isolation of ovarian follicles (eggs with their surrounding helper cells) is a key step in culture systems for large mammalian species, to promote continued growth. Yet, isolation methods may affect the follicle’s future developmental capacity. We evaluated two isolation strategies, mechanical micro-dissection (needle/scalpel blade) and enzymatic digestion (using Liberase blendzyme) on ovaries of domestic cats obtained via routine spay procedures. Mechanically isolated follicles displayed improved growth, survival, and indications of developmental competence in 14-day culture, compared with high concentration (1.4 Wünsch units/mL) enzyme-isolated follicles. However, mechanical isolation was not different from low (0.7 Wünsch units/mL) enzyme for these metrics, or for expression of key genes indicative of follicular cell functions. Further, differences in follicle growth/survival were not apparent until 7+ days in culture. Thus, ovarian follicle isolation strategies influence developmental potential in culture, and extended culture will be required to identify optimal methods for fertility preservation efforts.
6
Mester, B., B. P. Thomson e D. C. Eckery. "258. Characterisation of ovarian follicular growth in the brushtail possum". Reproduction, Fertility and Development 17, n.º 9 (2005): 104. http://dx.doi.org/10.1071/srb05abs258.
Texto completo da fonteResumo:
The number and size of follicles selected for ovulation differ between species. The aim of this study was to characterise antral follicular growth and determine the size when selection of the ovulatory follicle occurs in the monovular brushtail possum. For this study, antral follicles ≥ 1 mm were dissected from the ovaries of 31 adult female possums at different reproductive states and follicular fluid and granulosa cells were harvested from each individual follicle. Selection of the ovulatory follicle in the brushtail possum occurred when follicles reached between 2.5 and 2.8 mm in diameter. Based on the analysis of steroids in follicular fluid, before selection, most follicles produced varying amounts of oestradiol (E2), but very few if any produced progesterone (P4). After selection, the selected follicle continued to produce increasing amounts of E2 and P4, whereas most other follicles were steroidogenically inactive. Near the time of ovulation, presumably after the LH surge, P4 became the predominant steroid produced by the selected follicle and most other follicles once again produced varying amounts of E2. The number of granulosa cells per follicle was highly variable, but tended to increase with increasing diameter. Cell viability was very high, averaging about 95%. Interestingly, the morphology of granulosa cells changed markedly after selection becoming larger and granular in appearance. The weights of the vaginal cul-de-sac and uteri correlated well with the presence of a selected follicle. In ovaries from pregnant animals (n = 3), follicles grew up to 3.5 mm, and although they reached the size of a selected follicle during the follicular phase, E2 production by the other follicles was not suppressed and the weights of the cul-de-sac were less than those from non-pregnant animals with similar sized follicles. During anoestrus (n = 4), follicles did not grow beyond 2 mm and produced very little steroids.
7
Nagorcka, BN. "The reaction-diffusion (RD) theory of wool (hair) follicle initiation and development. II. Original secondary follicles". Australian Journal of Agricultural Research 46, n.º 2 (1995): 357. http://dx.doi.org/10.1071/ar9950357.
Texto completo da fonteResumo:
In an accompanying paper it was shown that a spatial prepattern mechanism based on a biochemical reaction referred to as a reaction-diffusion (RD) system is able to account for many aspects of the initiation and development of primary (P) wool follicles. In this paper the same RD system is applied to the initiation and development of original secondary (SO) follicles. Prepatterns are generated by solving the equations describing the reaction and diffusion of the chemical components of the RD system in early stage follicles. It is demonstrated that the prepattern mechanism can account for the loss of a sweat gland causing a change from P follicle initiation to SO follicle initiation. The RD system equations are also solved in the epidermis. The time sequence of prepatterns obtained in the epidermis account for the tendency of SO follicles to group with P follicles, by initiating in-between members of the trio group of P follicles as well as in between existing SO follicles. The prepatterns obtained did not account for the tendency of secondary follicles to initiate on the posterior side of the trio group. Good agreement was obtained between the predicted increase in total follicle density and the increase in follicle density observed during follicle initiation by Carter and Hardy (1947), provided full account was taken of the interaction between existing follicles and each new future generations of follicles. The prepattern mechanism provides a fundamental basis for an inverse genetic correlation between total P and SO follicle density and fibre diameter.
8
Holbech, L. N., K. D. Frederiksen, H. G. Pedersen, T. Greve e I. B. Bøgh. "206 FOLLICULAR GROWTH SUBSEQUENT TO FOLLICULAR ASPIRATION IN THE MARE". Reproduction, Fertility and Development 17, n.º 2 (2005): 253. http://dx.doi.org/10.1071/rdv17n2ab206.
Texto completo da fonteResumo:
Follicle aspiration has previously been used in mares as a research tool to remove growing and atretic follicles, in order to study follicular growth. The aim of the present study was to (1) evaluate the fate of the aspirated follicles, and (2) determine the point of selection of the dominant follicle subsequent to follicular aspiration. In six Standardbred mares, all follicles larger than 9 mm were removed by transvaginal ultrasound-guided aspiration (Day 0). Subsequent to follicular aspiration, the growth of follicles larger than 1 mm was monitored daily by ultrasonography from Day 0 to Day 7. Aspirated follicles were monitored to establish whether they refilled and continued to grow, or luteinized. The experiment was conducted in six replicates in each mare. On Day 1 after aspiration the largest and second largest follicles were 10.4 ± 0.8 mm (mean ± SEM) and 7.8 ± 0.6 mm, respectively. On Day 7 the largest follicle and the second largest follicle were 25.7 ± 1.2 mm and 18.6 ± 1.2 mm, respectively. In 10/209 follicles, the follicular cavity refilled subsequent to aspiration with non-echogenic fluid and the follicle diameter increased during the following 7 days. Four of the ten aspirated and refilled follicles grew to become the largest follicles, whereas the remaining six follicles did not reach dominance. A further three aspirated follicles grew and ovulated on Day 5. In one case, an aspirated follicle refilled and continued to grow after an oocyte had been recovered. However, from these preliminary results, the growth pattern of the aspirated follicle can not be predicted on the basis of whether or not the oocyte was removed during the aspiration session. Preliminary results of this study indicate that follicular selection for dominance as determined by follicular size difference may already have occurred on Day 1 after aspiration. Furthermore, follicles that refill with fluid and continue to grow after aspiration may pose a problem when follicular growth and selection are studied. This research was funded by the Danish Research Agency, project no. 23-02-0133.
9
Gastal, E. L., M. O. Gastal, M. A. Beg e O. J. Ginther. "Interrelationships among follicles during the common-growth phase of a follicular wave and capacity of individual follicles for dominance in mares". Reproduction 128, n.º 4 (outubro de 2004): 417–22. http://dx.doi.org/10.1530/rep.1.00259.
Texto completo da fonteResumo:
The changing diameter interrelationships among follicles during the interval from emergence to deviation (common-growth phase) were studied in 59 mares. All follicles of ≥6.0 mm were ablated 10 days after ovulation. The four largest follicles of the postablation wave were ranked D1, D2, D3 and D4 at the expected beginning of deviation (D1 ≥ 20.0 mm), according to descending diameter. The four follicles were also ranked independently, according to order of emergence at 6.0–6.9 mm as E1 (first to emerge), E2, E3 and E4. The follicles emerged during 1.3 ± 0.1 to 3.1 ± 0.1 days, and expected deviation began 6.5 ± 0.1 days after ablation. The frequency of emerging follicles becoming the largest follicle at the beginning of deviation was different (P < 0.0001; chi-square test) among follicles E1 (61%), E2 (25%), E3 (9%) and E4 (5%). There were no differences in growth rates among the four follicles throughout the common-growth phase (overall, 2.8 ± 0.04 mm/day). The differences in diameters between follicles E1 and E2 were similar between 3 days (2.7 ± 0.2 mm) and 6 days (2.9 ± 0.4 mm) after ablation. In controls and after ablation of D1; D1 and D2; or D1, D2 and D3 at the expected beginning of deviation, the largest remaining follicle became dominant in 26 of 34 mares (76%). In 10 of 15 mares (67%), the second-largest follicle became dominant when the largest follicle was ablated 1 or 2 days after the expected beginning of deviation. Results indicated the following: 1) the first follicle to emerge maintained its diameter advantage in most mares and average diameter growth rates were similar among the four follicles throughout the common-growth phase; 2) the hypothesis was supported that the capacity for dominance is similar among the four largest follicles at the beginning of deviation, but dominance by a smaller follicle is blocked when a larger follicle is present; and 3) the second-largest follicle retained the capacity for dominance in most mares for as long as 2 days after the beginning of deviation.
10
Langbeen, A., E. P. A. Jorssen, E. Fransen, A. P. A. Rodriguez, M. Chong García, J. L. M. R. Leroy e P. E. J. Bols. "Characterization of freshly retrieved preantral follicles using a low-invasive, mechanical isolation method extended to different ruminant species". Zygote 23, n.º 5 (17 de julho de 2014): 683–94. http://dx.doi.org/10.1017/s0967199414000331.
Texto completo da fonteResumo:
SummaryDue to the increased interest in preantral follicular physiology, non-invasive retrieval and morphological classification are crucial. Therefore, this study aimed: (1) to standardize a minimally invasive isolation protocol, applicable to three ruminant species; (2) to morphologically classify preantral follicles upon retrieval; and (3) to describe morphological features of freshly retrieved follicles compared with follicle characteristics using invasive methods. Bovine, caprine and ovine ovarian cortex strips were retrieved from slaughterhouse ovaries and dispersed. This suspension was filtered, centrifuged, re-suspended and transferred to a Petri dish, to which 0.025 mg/ml neutral red (NR) was added to assess the viability of the isolated follicles. Between 59 and 191 follicles per follicle class and per species were collected and classified by light microscopy, based on follicular cell morphology. Subsequently, follicle diameters were measured. The proposed isolation protocol was applicable to all three species and showed a significant, expected increase in diameter with developmental stage. With an average diameter of 37 ± 5 μm for primordial follicles, 47 ± 6.3 μm for primary follicles and 67.1 ± 13.1 μm for secondary follicles, no significant difference in diameter among the three species was observed. Bovine, caprine and ovine follicles (63, 59 and 50% respectively) were graded as viable upon retrieval. Using the same morphological characteristics as determined by invasive techniques [e.g. haematoxylin–eosin (HE) sections], cumulus cell morphology and follicle diameter could be used routinely to classify freshly retrieved follicles. Finally, we applied a mechanical, minimally invasive, follicle isolation protocol and extended it to three ruminant species, yielding viable preantral follicles without compromising further in vitro processing and allowing routine follicle characterization upon retrieval.
11
Duarte, Ana Beatriz Graça, Roberta Nogueira Chaves, Valdevane Rocha Araújo, Juliana Jales Celestino, Gerlane Modesto Silva, Cláudio Afonso Pinho Lopes, Líliam Mara Trevisan Tavares, Cláudio Cabral Campelo e José Ricardo de Figueiredo. "Follicular interactions affect the in vitro development of isolated goat preantral follicles". Zygote 19, n.º 3 (28 de outubro de 2010): 215–27. http://dx.doi.org/10.1017/s0967199410000237.
Texto completo da fonteResumo:
SummaryThe aim of this study was to evaluate the influence of the number of follicles per drop (one or three) and antral follicles on in vitro development of isolated goat preantral follicles. Preantral follicles were isolated through microdissection and distributed individually (control) or in groups of three follicles (treatment) in microdroplets of α-MEM with or without 1000 ng/ml follicle stimulating hormone (FSH) for Experiments 1 and 2, respectively. Experiment 3 was divided into four treatments according to the presence of one or three preantral follicles, associated or not with antral follicles. After culture, oocytes were retrieved from morphologically normal follicles and submitted to in vitro maturation (IVM) and live/dead fluorescent labelling. Results of Experiment 1 (basic medium without FSH) showed that culture of preantral follicles in groups enhances viability, growth and antrum formation after 12 days. However, in the presence of FSH (Experiment 2), only the recovery rate of fully grown oocytes for IVM was significantly affected by grouping of follicles. In Experiment 3, in general, co-culture of preantral follicles with an early antral follicle had a detrimental effect on viability, antrum formation and production of oocytes for IVM. In conclusion, the performance of in vitro culture of goat preantral follicles is affected by the number of follicles per drop, the presence of an antral follicle and FSH.
12
Moore, GPM, N. Jackson, K. Isaacs e G. Brown. "Development and density of wool follicles in Merino sheep selected for single fibre characteristics". Australian Journal of Agricultural Research 47, n.º 8 (1996): 1195. http://dx.doi.org/10.1071/ar9961195.
Texto completo da fonteResumo:
Wool follicles are classified into 3 major types: primary (P), original secondary (SO), and derived secondary (SD). They are formed during fetal life as successive waves of initiation pass through the skin. P follicles are the first to be initiated. SO follicles develop between the primaries and are separated from them at non-randomly distributed sites. SD follicles are the last to be initiated and branch from SO and other SD follicles. We have measured the densities of these follicles in 4 lines of sheep selected for different fleece characters. Primary follicle and total follicle densities (NP and NP + NS) were estimated by conventional procedures. The densities of pilary canals were also obtained to provide a measure of Np + NSO. Follicle counts in both adult and fetal animals showed that NP and NP + NSO were relatively constant across the lines. Predominantly, density differences were due to variations in the numbers of follicles initiated during the last wave, forming the derived secondary population. Changes in follicle densities were therefore effected by developmental mechanisms that increase or decrease the extent of branching rather than by altering the numbers of P and SO follicles. The results suggest firstly that the numbers of initiation sites for P or SO follicle formation in the fetus, corresponding to the pilary canals of adult skin, are limited. Secondly, the skin has the capacity to continue to initiate follicles after most or all of the sites have been occupied. It is concluded that the mechanisms controlling follicle initiation site densities and total follicle densities are independently regulated in the sheep. The observations are discussed in relation to factors that influence the densities of the different follicle types. The results have practical implications for changing fleece weight and fibre diameter through selective breeding.
13
Chen, Yu-Ying, Daniela D. Russo, Riley S. Drake, Francesca E. Duncan, Alex K. Shalek, Brittany A. Goods e Teresa K. Woodruff. "Single-cell transcriptomics of staged oocytes and somatic cells reveal novel regulators of follicle activation". Reproduction 164, n.º 2 (1 de agosto de 2022): 55–70. http://dx.doi.org/10.1530/rep-22-0053.
Texto completo da fonteResumo:
In brief Proper development of ovarian follicles, comprised of an oocyte and surrounding somatic cells, is essential to support female fertility and endocrine health. Here, we describe a method to isolate single oocytes and somatic cells from the earliest stage follicles, called primordial follicles, and we characterize signals that drive their activation. Abstract Primordial follicles are the first class of follicles formed in the mammalian ovary and are comprised of an oocyte surrounded by a layer of squamous pre-granulosa cells. This developmental class remains in a non-growing state until individual follicles activate to initiate folliculogenesis. What regulates the timing of follicle activation and the upstream signals that govern these processes are major unanswered questions in ovarian biology. This is partly due to the paucity of data on staged follicle cells since isolating and manipulating individual oocytes and somatic cells from early follicle stages are challenging. To date, most studies on isolated primordial follicles have been conducted on cells collected from animal-age- or oocyte size-specific samples, which encompass multiple follicular stages. Here, we report a method for collecting primordial follicles and their associated oocytes and somatic cells from neonatal murine ovaries using liberase, DNase I, and Accutase. This methodology allows for the identification and collection of follicles immediately post-activation enabling unprecedented interrogation of the primordial-to-primary follicle transition. Molecular profiling by single-cell RNA sequencing revealed that processes including organelle disassembly and cadherin binding were enriched in oocytes and somatic cells as they transitioned from primordial to the primary follicle stage. Furthermore, targets including WNT4, TGFB1, FOXO3, and a network of transcription factors were identified in the transitioning oocytes and somatic cells as potential upstream regulators that collectively may drive follicle activation. Taken together, we have developed a more precise characterization and selection method for studying staged-follicle cells, revealing several novel regulators of early folliculogenesis.
14
Matti, N., H. F. Irving-Rodgers, W. M. Bonner, N. Hatzirodos, T. R. Sullivan e R. J. Rodgers. "534. CO-ORDINATED GENE EXPRESSION IN BOVINE GRANULOSA CELLS PRECEDES FOLLICULAR DOMINANCE". Reproduction, Fertility and Development 21, n.º 9 (2009): 132. http://dx.doi.org/10.1071/srb09abs534.
Texto completo da fonteResumo:
During growth of bovine follicles, one emerges as the largest and dominant follicle. What regulates dominance remains unknown, but candidates include oestradiol, TGFB1, and recently CYP11A1 and focal intra-epithelial matrix (focimatrix). The two to four largest follicles were dissected from pairs of bovine ovaries and follicular fluid collected. A portion of the follicle wall was histologically classified for follicle health or atretia, and granulosa cells harvested for quantitative RT-PCR. Messenger RNA levels of focimatrix (COL4A1, LAMB2, HSPG2), steroidogenic enzymes (CYP11A1, CYP19A1) and TGFB1 genes were measured. Follicular fluid progesterone and oestradiol concentrations were measured by RIA. Follicles were identified as pre-deviated (before size-deviation) if the largest two or more healthy follicles were of equal size (6.7±0.1 mm, n = 14 animals, 35 follicles), and as post-deviated (after size-deviation) if they differed in size by 0.5–1.0 mm (7.2±0.2 mm; n = 11 animals, 26 follicles). For analyses, pre-deviated follicles were grouped into either the highest (oestradiol, CYP11A1) or lowest (TGFB1) expression (n = 14) and compared to the remaining follicles (n = 21). Deviated follicles were classified into dominant (n = 12) and subordinate (n = 14) based on diameter. Dominant follicles did not differ from subordinate follicles in any parameters measured, but were significantly larger than subordinate or pre-deviated follicles (P<0.01). For pre-deviated follicles grouped on oestradiol no parameters differed significantly, and when grouped on TGFB1, LAMB2 (P<0.05), HSPG (P<0.05), CYP19A1 (P<0.05) and TGFB1 (P<0.01) differed but levels were lower, not higher as expected. When grouped on CYP11A1, COL4A1 (P<0.05), LAMB2 (P<0.01), HSPG2 (P<0.01) and CYP19A1 (P<0.001) were significantly elevated in the high CYP11A1 group. This suggests that CYP11A1 and focimatrix might be important in follicle dominance.
15
Nie, Ruixue, Xiaotong Zheng, Wenhui Zhang, Bo Zhang, Yao Ling, Hao Zhang e Changxin Wu. "Morphological Characteristics and Transcriptome Landscapes of Chicken Follicles during Selective Development". Animals 12, n.º 6 (11 de março de 2022): 713. http://dx.doi.org/10.3390/ani12060713.
Texto completo da fonteResumo:
Ovarian follicle selection largely depends on the transition of granulosa cells from an undifferentiated to a fully differentiated state, which is accompanied by morphological and functional changes in follicles. The processes and transcriptional regulation of follicles during follicle selection are unclear; we thus used follicles from the prehierarchal to the hierarchal stage to investigate histology, reproductive endocrinology, and transcription. The morphology of follicles changed markedly during follicle selection. The numbers of large white, small yellow, and large yellow follicles (LWF, SYF, and LYF, respectively) were 11.83 ± 2.79, 6.83 ± 2.23, and 1.00, respectively, per ovary. LYF showed thicker granulosa cell layers than those of other prehierarchal follicles. Progesterone concentrations were significantly higher in LYF than that in LWF and SYF. In total, 16,823 genes were positively expressed in LWF, SYF, and LYF. Among follicle types, 1290 differentially expressed genes were enriched regarding cell differentiation, blood vessel morphogenesis, and response to steroid hormones. Candidate genes associated with follicle selection participated in the Wnt signaling pathway, steroid hormone biosynthesis, and the TGF-β signaling pathway. We produced insights into crucial morphological characteristics of transcriptional regulation in follicle development. Our results provide an important basis for revealing the mechanism of follicle selection and potential impact on the poultry industry.
16
Gastal, M. O., K. A. Alves, B. G. Alves, G. D. A. Gastala, S. G. S. de Tarso, J. R. Figueiredo, M. L. Gambarini e E. L. Gastal. "123 THE MARE MODEL TO STUDY HOW OVARIAN DYNAMICS AFFECTS PREANTRAL FOLLICLE FEATURES". Reproduction, Fertility and Development 28, n.º 2 (2016): 191. http://dx.doi.org/10.1071/rdv28n2ab123.
Texto completo da fonteResumo:
The mare has been strongly advocated by several research groups as an important comparative animal model to study antral follicular dynamics in women due to some similarities in reproductive events. More recently, the mare has also been suggested as a potential model for studies related to preantral follicles. The search for an appropriate animal model for comparative studies of preantral follicle population, density, and distribution has been a major focus of recent ovarian translational studies. The aim of the present study was to investigate the influence of reproductive phase (anestrous v. diestrous) and ovarian structures (antral follicles and corpus luteum) on the quality, class distribution, number, and density of preantral follicles, and stromal cell density. Ovarian fragments were harvested in vivo from young, healthy mares (n = 10) during both reproductive phases using a biopsy pickup method and submitted to histological analysis. All evaluations and measurements were performed by a single operator and only follicles with a visible nucleus was considered for follicle counting. Data were analysed by Kruskal-Wallis test, Wilcoxon-Mann-Whitney test, and Spearman’s correlation. A total of 142 ovarian biopsy fragments were collected (mean, 3.7 fragments per mare in each reproductive phase) and 13 462 histological sections were evaluated. Overall, 1493 preantral follicles were recorded with a mean of 10.5 ± 1.7 follicles per ovarian fragment [range, 0 to 165; mean coefficient of variation (CV) = 195%]. The mean follicle density was 2.7 follicles per cm2 (range, 0 to 39; CV = 214%) and differed (P < 0.05) among mares. The mean preantral follicle and ovarian stromal cell densities were greater (P < 0.05) in the diestrous phase and a positive correlation of stromal cell density with the number and density of preantral follicles was observed. The mean area (mm2) of ovarian structures increased (P < 0.05) in the diestrous phase and had positive correlations with number of preantral follicles, follicle density, and stromal cell density. Biopsy fragments collected from ovaries during the diestrous phase had a higher (P < 0.05) follicle density, stromal cell density, and proportion of normal preantral follicles. In conclusion, our results showed (1) the diestrous phase influenced positively the preantral follicle quality, class distribution, and follicle and stromal cell densities; (2) the area of ovarian structures was positively correlated with the follicle and stromal cell densities; and (3) the presence of an active corpus luteum had a positive effect on the quality of preantral follicles and follicle and stromal densities. Therefore, herein we demonstrated that reproductive phases and ovarian structures induce changes in preantral follicle features and stromal cell density favouring the harvesting of ovarian fragments containing an appropriate number of healthy preantral follicles. These findings reinforce the concept of the use of the mare as an appropriate model to provide comparative insights about preantral follicle density and ovarian plasticity.
17
Yoon, Ki-Won, Tae-Young Shin, Jong-Im Park, Sangho Roh, Jeong M. Lim, Byeong-Chun Lee, Woo-Suk Hwang e Eun-Song Lee. "Development of porcine oocytes from preovulatory follicles of different sizes after maturation in media supplemented with follicular fluids". Reproduction, Fertility and Development 12, n.º 4 (2000): 133. http://dx.doi.org/10.1071/rd00027.
Texto completo da fonteResumo:
The development of porcine oocytes from large (3.1–8.0 mm in diameter) or small (<3.1 mm) follicles was examined after maturation culture in medium containing porcine follicular fluid (pFF). Large follicles yielded larger (256 m v. 221 m; P<0.05) cumulus–oocyte complexes and more (22 v. 14%) morphologically normal oocytes than small follicles (Experiment 1). In Experiments 2–4, maturation media supplemented with mixed pFF (10%) from small and large follicles was used. More oocytes from large follicles matured (58% v. 91%), formed pronuclei (81% v. 90%) and developed to the blastocyst stage (2% v. 10%) than oocytes from small follicles. In Experiments 5–7, the effects of pFF collected from either small or large follicles on oocyte development were examined. Regardless of the source of oocytes, large-follicle-derived pFF more significantly enhanced preimplantation development than did small-follicle-derived pFF. The highest rate of blastocyst formation (16%) was found when oocytes from large follicles were cultured in maturation medium containing large-follicle-derived pFF. These results suggest that oocytes from large follicles have greater developmental potential than oocytes from small follicles, and that the origin of pFF, which is added to the maturation media, might be an important factor for improving in vitro development of porcine oocytes.
18
Xiao, Shuo, Francesca E. Duncan, Lu Bai, Catherine T. Nguyen, Lonnie D. Shea e Teresa K. Woodruff. "Size-specific follicle selection improves mouse oocyte reproductive outcomes". REPRODUCTION 150, n.º 3 (setembro de 2015): 183–92. http://dx.doi.org/10.1530/rep-15-0175.
Texto completo da fonteResumo:
Encapsulated in vitro follicle growth (eIVFG) has great potential to provide an additional fertility preservation option for young women and girls with cancer or other reproductive health threatening diseases. Currently, follicles are cultured for a defined period of time and analyzed as a cohort. However, follicle growth is not synchronous, and culturing follicles for insufficient or excessive times can result in compromised gamete quality. Our objective is to determine whether the selection of follicles based on size, rather than absolute culture time, better predict follicle maturity and oocyte quality. Multilayer secondary mouse follicles were isolated and encapsulated in 0.25% alginate. Follicles were cultured individually either for defined time periods or up to specific follicle diameter ranges, at which point several reproductive endpoints were analyzed. The metaphase II (MII) percentage after oocyte maturation on day 6 was the highest (85%) when follicles were cultured for specific days. However, if follicles were cultured to a terminal diameter of 300–350 μm irrespective of absolute time in culture, 93% of the oocytes reached MII. More than 90% of MII oocytes matured from follicles with diameters of 300–350 μm showed normal spindle morphology and chromosome alignment, 85% of oocytes showed two pronuclei after IVF, 81% developed into the two-cell embryo stage and 38% developed to the blastocyst stage, all significantly higher than the percentages in the other follicle size groups. Our study demonstrates that size-specific follicle selection can be used as a non-invasive marker to identify high-quality oocytes and improve reproductive outcomes during eIVFG.
19
Ohleth, KM, Q. Zhang e CA Bagnell. "Relaxin protein and gene expression in ovarian follicles of immature pigs". Journal of Molecular Endocrinology 21, n.º 2 (1 de outubro de 1998): 179–87. http://dx.doi.org/10.1677/jme.0.0210179.
Texto completo da fonteResumo:
Relaxin production by the ovarian follicle of gonadotropin-primed, prepubertal gilts is well documented. As far as we are aware, a source of relaxin in pig follicles, independent of gonadotropins, has not yet been reported. Therefore, the objective of this study was to determine whether relaxin is produced in porcine follicles in the absence of exogenous or cyclic gonadotropins. In immature pigs, immunoreactive relaxin was detected in fluids from small (1-3 mm), medium (4-5 mm) and large (>6 mm) follicles and localized to the theca interna of large follicles. Relaxin levels in follicular fluid significantly increased with follicle size (P<0.05). Relaxin mRNA was detected in whole small- and medium-sized follicles. In large follicles, the relaxin gene was expressed in thecal layers, but not granulosa cells. The abundance of relaxin transcript did not change with follicle size. In summary, relaxin protein and mRNA were detected in porcine follicles from immature animals, indicating that relaxin is produced in the porcine follicle in the absence of exogenous or cyclic gonadotropins. Relaxin's in vitro growth effects on porcine granulosa and theca cells support this follicular relaxin as a growth modulator during porcine follicular development.
20
Kaune, Heidy, Sairah Sheikh e Suzannah A. Williams. "Analysis of in vitro follicle development during the onset of premature ovarian insufficiency in a mouse model". Reproduction, Fertility and Development 29, n.º 8 (2017): 1538. http://dx.doi.org/10.1071/rd15524.
Texto completo da fonteResumo:
Premature ovarian insufficiency (POI) occurs in 1% of women under 40 years of age and is predominantly idiopathic. In a transgenic mouse model of follicular POI, the Double Mutant (DM), female mice are fertile at 6 weeks of age, become infertile by 9 weeks and exhibit POI by 3 months. DM female mice generate oocytes lacking mucin O-glycans and complex N-glycans due to deletion of core 1 synthase, glycoprotein-N-acetylgalactosamine 3-β-galactosyltransferase 1 (C1galt1) and mannoside acetylglucosaminyltransferase 1 (Mgat1) respectively (DM, C1galt1F/FMgat1F/F:ZP3Cre; Control, C1galt1F/FMgat1F/F). To determine whether DM follicle development could be improved in a controlled environment, follicles from DM and Control mice were cultured individually and follicle growth, morphology, survival and antrum formation were evaluated. DM ovaries were more rigid than Control ovaries at 3, 6 and 9 weeks, which was exacerbated with age, resulting in a failure to isolate follicles from 9 week-old DM females. DM follicles had decreased survival compared with Control follicles from females at 3 and 6 weeks of age. Furthermore, survival rate of DM follicles decreased with age between 3 and 6 weeks. DM follicles at both 3 and 6 weeks had accelerated follicle growth and altered antrum formation during the first few days of culture but, after 6 days, follicles were equivalent in size to the Controls. In conclusion, a population of DM follicles retain the potential to develop in vitro, and therefore follicle culture offers a reliable method to generate antral follicles from preantral follicles after the onset of POI in these female mice.
21
Visser, Jenny A., Alexandra L. L. Durlinger, Isolde J. J. Peters, Edwin R. van den Heuvel, Ursula M. Rose, Piet Kramer, Frank H. de Jong e Axel P. N. Themmen. "Increased Oocyte Degeneration and Follicular Atresia during the Estrous Cycle in Anti-Müllerian Hormone Null Mice". Endocrinology 148, n.º 5 (1 de maio de 2007): 2301–8. http://dx.doi.org/10.1210/en.2006-1265.
Texto completo da fonteResumo:
Anti-Müllerian hormone (AMH) plays an important role in folliculogenesis. AMH null mice display an increased recruitment of primordial follicles. Nevertheless, these mice do not have proportionally more preovulatory follicles. Therefore, AMH null mice provide an interesting genetic model to study the regulation of species-specific number of preovulatory follicles. We studied the follicle pool throughout the estrous cycle at 4 months of age. Analysis of the follicle pool revealed that AMH null mice have an increased and earlier cyclic recruitment of growing follicles despite a blunted FSH surge at estrus. However, FSH levels at estrus were apparently too low to support growth to the preovulatory stage because an increased level of atresia was observed, which neutralized the increased cyclic recruitment. When AMH null mice were subjected to a superovulation scheme, the rise in FSH levels resulted in the rescue of the recruited cohort of growing follicles. Analysis of the follicle pool also revealed that the increased recruitment of primordial follicles in AMH null mice was neutralized by an increased loss of follicles during the transition from small preantral to large preantral follicle. This major loss of follicles was not completely reflected by a corresponding augmentation of atresia but did correspond with an increased number of oocyte remnants observed in AMH null mice. We conclude that a combination of increased oocyte degeneration and increased follicular atresia neutralizes the increased initial and cyclic recruitment in AMH null mice to a normal number of preovulatory follicles.
22
Silva, J. R. V., T. Tharasanit, M. A. M. Taverne, G. C. van der Weijden, R. R. Santos, J. R. Figueiredo e R. van den Hurk. "The activin-follistatin system and in vitro early follicle development in goats". Journal of Endocrinology 189, n.º 1 (abril de 2006): 113–25. http://dx.doi.org/10.1677/joe.1.06487.
Texto completo da fonteResumo:
The aim of the present study was to investigate the effects of activin-A and follistatin on in vitro primordial and primary follicle development in goats. To study primordial follicle development (experiment 1), pieces of ovarian cortex were cultured in vitro for 5 days in minimal essential medium (MEM) supplemented with activin-A (0, 10 or 100 ng/ml), follistatin (0, 10 or 100 ng/ml) or combinations of the two. After culture, the numbers of primordial follicles and more advanced follicle stages were calculated and compared with those in non-cultured tissue. Protein and mRNA expression of activin-A, follistatin, Kit ligand (KL), growth differentiation factor-9 (GDF-9) and bone morphogenetic protein-15 (BMP-15) in non-cultured and cultured follicles were studied by immunohistochemistry and PCR. To evaluate primary follicle growth (experiment 2), freshly isolated follicles were cultured for 6 days in MEM plus 100 ng/ml activin-A, 100 ng/ml follistatin or 100 ng/ml activin-A plus 200 ng/ml follistatin. Morphology, follicle and oocyte diameters in cultured tissue and isolated follicles before and after culture were assessed. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) reactions were performed to study DNA fragmentation in follicles. In experiment 1, it was found that goat primordial follicles were activated to develop into more advanced stages, i.e. intermediate and primary follicles, during in vitro culture, but neither activin-A nor follistatin affected the number of primordial follicles that entered the growth phase. Activin-A treatment enhanced the number of morphologically normal follicles and stimulated their growth during cortical tissue culture. The effects were, however, not counteracted by follistatin. The follicles in cultured goat tissue maintained their expression of proteins and mRNA for activin-A, follistatin, KL, GDF-9 and BMP-15. Fewer than 30% of the atretic follicles in cultured cortical tissue had TUNEL-positive (oocyte or granulosa) cells. Activin-A did not affect the occurrence of TUNEL-positive cells in follicles within cortical tissue. In experiment 2, addition of activin-A to cultured isolated primary follicles significantly stimulated their growth, the effect being counteracted by follistatin. Absence of such a neutralizing effect of follistatin in the cultures with ovarian cortical tissue can be due to lower dose of follistatin used and incomplete blockage of activin in these experiments. In contrast to cortical enclosed atretic follicles, all atretic follicles that had arisen in cultures with isolated primary follicles had TUNEL-positive cells, which points to differences between isolated and ovarian tissue-enclosed follicles with regard to the followed pathways leading to their degeneration. In summary, this in vitro study has demonstrated that cultured goat primordial follicles are activated to grow and develop into intermediate and primary follicles. During in vitro culture, the follicles maintain their ability to express activin-A, follistatin, KL, GDF-9 and BMP-15. The in vitro growth and survival of activated follicles enclosed in cortical tissue and the in vitro growth of isolated primary follicles are stimulated by activin-A.
23
Young, Fiona, John Drummond, Emma Akers, Louise Bartle, David Kennedy e Mohammad Asaduzzaman. "Effects of ovarian disaggregation on adult murine follicle yield and viability". Reproduction, Fertility and Development 29, n.º 12 (2017): 2400. http://dx.doi.org/10.1071/rd16398.
Texto completo da fonteResumo:
Follicles are isolated from ovaries for numerous reasons, including IVM, but adult murine yields are <2 follicles mg−1. The aim of the present study was to optimise ovarian disaggregation and develop methods applicable to the rapid screening of follicle viability. Ovaries from adult mice (n = 7) were halved and disaggregated mechanically, or by using collagenase IV (Col-IV; 590 U mL−1) or animal origin-free collagenase IV (AOF) at 590 or 1180 U mL−1. Isolated follicles were stained with 4′,6′-diamidino-2-phenylindole (DAPI; nuclei), chloromethyl-X-rosamine (CMXRos; mitochondria) or fluorescein isothiocyanate-conjugated anti-α-tubulin antibody. Follicle diameters and staining were measured and analysed using ImageJ, and data analysed using GraphPad Prism. Col-IV disaggregation yielded the highest number of follicles (17 ± 10 follicles mg−1 ovarian tissue). All disaggregation methods released more secondary follicles (86 ± 20 per ovary; P < 0.05) than any other size cohort. Mechanical and Col-IV disaggregation yielded similar numbers of morphologically intact follicles, whereas AOF disaggregation caused more damage (P < 0.01). As the morphological disruption increased, DAPI and CMXRos staining decreased (P < 0.05), and tubulin localisation became more heterogeneous. Col-IV disaggregation gave the best yield of morphologically intact follicles containing viable granulosa cells. In conclusion, we improved adult murine follicle yields and applied molecular markers to assess follicle morphology, cellular cytoskeleton and mitochondrial function.
24
Ostuni, Angela, Maria Pina Faruolo, Carmen Sileo, Agata Petillo e Raffaele Boni. "Effect of follicle size and atresia grade on mitochondrial membrane potential and steroidogenic acute regulatory protein expression in bovine granulosa cells". Zygote 26, n.º 6 (dezembro de 2018): 476–84. http://dx.doi.org/10.1017/s0967199418000564.
Texto completo da fonteResumo:
SummaryDuring follicular development, granulosa cells undergo functional and structural changes affecting their steroidogenic activity. Oestrogen synthesis mainly occurs in the endoplasmic reticulum and relies on aromatase activity to convert androgens that arise from theca cells. In the present study, indicators of mitochondria-related steroidogenic capacity, as steroidogenic acute regulatory (StAR) protein expression and mitochondrial membrane potential (MMP), have been evaluated in bovine granulosa cells (GCs) and related to follicle growth and atresia. Atresia was estimated by morphological examination of follicle walls and cumulus–oocyte complexes (COC) and assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay for apoptosis detection. Bovine ovarian follicles were macroscopically classified according to their atresia grade and grouped into small, medium or large follicles. After follicle opening, the COCs were morphologically classified for follicle atresia and the GCs were collected. Granulosa cells were fixed for immunofluorescence (IF) and TUNEL assay, frozen for western blotting (WB) or freshly maintained for MMP analyses. StAR protein expression was assessed using both IF and WB analyses. The follicle atresia grade could be efficiently discriminated based on either follicle wall or COC morphological evaluations. Granulosa cells collected from small non-atretic follicles showed a higher (P <0.01) MMP and WB-based StAR protein expression than small atretic follicles. For IF analysis, StAR protein expression in large atretic follicles was higher (P <0.05) than that in large non-atretic follicles. These results suggest a role played by mitochondria in GC steroidogenic activity, which declines in healthy follicles along with their growth. In large follicles, steroidogenic activity increases with atresia and is possibly associated with progesterone production.
25
Castilho, A. C. S., M. F. Machado, D. M. Guerra, R. Ereno, C. M. Barros, C. A. Price e J. Buratini Jr. "230 EXPRESSION OF mRNA ENCODING FGF10 AND COGNATE RECEPTORS (FGFR1B AND FGFR2B) AROUND FOLLICLE DEVIATION IN NELORE HEIFERS". Reproduction, Fertility and Development 22, n.º 1 (2010): 273. http://dx.doi.org/10.1071/rdv22n1ab230.
Texto completo da fonteResumo:
A member of the FGF7 subfamily, FGF10 acts via FGFR2B and FGFR1B. In bovine antral follicles, FGF-10 was detected in oocytes and theca cells (TC). Levels of mRNA were negatively correlated with intrafollicular concentrations of estradiol, and FGF10 inhibited estradiol production from granulosa cells (GC). In Nellore (Bos indicus), morphological divergence occurs on average 2.5 days after ovulation, when dominant follicle diameter is around 6.0 mm. To gain insight into the involvement of the FGF10 system in the control of follicle selection, we assessed mRNA expression of FGF10 in TC and of FGFR1B and FGFR2B in GC from dominant and subordinate follicles around deviation in Nellore heifers. Thirteen Nellore heifers were hormonally synchronized, and ovulation was detected by ultrasound monitoring every 12 h. Heifers were slaughtered 2 (n =4), 2.5 (n = 5), and 3 (n = 4) days after ovulation. Granulosa cells and TC were separated from the 2 largest follicles and submitted to total RNA extraction. mRNA abundance of CYP19 (aromatase), FGF10, FGFR1B, and FGFR2B was measured by real-time RT-PCR and normalized by the expression of cyclophilin A (CYCA) and GAPDH, for TC and GC, respectively. Dominant and subordinate follicles were considered those expressing the greatest and second-greatest abundance of CYP19 mRNA in GC within each heifer. Effects of follicle status and day on CYP19, FGF10, FGFR2B, and FGFR1B mRNA abundance were tested by ANOVA. On Day 2, FGFR2B mRNA abundance was greater in GC of subordinate follicles compared with dominant follicles (P = 0.006), and that of FGF10 in TC tended to exhibit the same pattern (P = 0.06). Follicle diameter was not different between dominant and subordinate follicles on Day 2 (5.5 ± 0 v. 5.12 ± 0.3 cm). On Day 2.5, FGF10 expression was greater in TC from subordinate follicles (P = 0.01), and FGFR2B expression in GC was no longer different between dominant and subordinate follicles. Follicle diameter was greater in dominant follicles on Day 2.5 (6.7 ± 0.2 v. 5.8 ± 0.3 cm; P = 0.04). On Day 3, no differences were observed between dominant and subordinate follicles for any of the genes assessed. mRNA expression of FGFR1B in GC did not change with follicle status or day. In conclusion, expression of FGF10 and FGFR2B was decreased in dominant follicles around morphological divergence, suggesting their involvement in the mechanisms controlling dominant follicle selection. As FGF10 inhibits estradiol production of GC, we propose that FGF10 and FGFR2B are suppressed in the dominant follicle to allow acquisition of full steroidogenic capacity. This research was supported by FAPESP.
26
Eichmüller, Stefan, Carina van der Veen, Ingrid Moll, Barbara Hermes, Udo Hofmann, Sven Müller-Röver e Ralf Paus. "Clusters of Perifollicular Macrophages in Normal Murine Skin: Physiological Degeneration of Selected Hair Follicles by Programmed Organ Deletion". Journal of Histochemistry & Cytochemistry 46, n.º 3 (março de 1998): 361–70. http://dx.doi.org/10.1177/002215549804600310.
Texto completo da fonteResumo:
In back skin sections from adolescent C57BL/6 mice, regularly distributed, perifollicular inflammatory cell clusters (PICC) were found located around the distal noncycling portion of about 2% of all hair follicles examined. The PICC and the affected hair follicles were characterized during spontaneously developed or induced hair cycle stages, using antibodies against MHC Class II,F4/80, ER-MP23, NLDC 145, CD4, CD8, γδTCR, IL-1 receptor, and ICAM-1. PICC consisted predominantly of macrophages (MAC), accompanied by a few CD4+ cells, whereas γδTCR+ and CD8+ cells were absent. During anagen and catagen, some of the PICC+ hair follicles showed variable degenerative phenomena reminiscent of scarring alopecia: thickened basement membrane, ectopic MHC II expression, MAC infiltration into the follicle epithelium, and signs of keratinocyte apoptosis. Loss of distal outer root sheath keratinocytes was detected in 10% of PICC+ hair follicles (0.2% of all hair follicles). Because PICC were located in the vicinity of the bulge region, MAC-dependent damage to follicle stem cells might eventually lead to follicle degeneration. These perifollicular MAC clusters around selected hair follicles may indicate the existence of a physiological program of MAC-dependent controlled follicle degeneration by which damaged or malfunctioning follicles are removed by programmed organ deletion (POD).
27
Schauer, S. N., S. D. Sontakke, E. D. Watson, C. L. Esteves e F. X. Donadeu. "Involvement of miRNAs in equine follicle development". REPRODUCTION 146, n.º 3 (setembro de 2013): 273–82. http://dx.doi.org/10.1530/rep-13-0107.
Texto completo da fonteResumo:
Previous evidence fromin vitrostudies suggests specific roles for a subset of miRNAs, including miR-21, miR-23a, miR-145, miR-503, miR-224, miR-383, miR-378, miR-132, and miR-212, in regulating ovarian follicle development. The objective of this study was to determine changes in the levels of these miRNAs in relation to follicle selection, maturation, and ovulation in the monovular equine ovary. In Experiment 1, follicular fluid was aspirated during ovulatory cycles from the dominant (DO) and largest subordinate (S) follicles of an ovulatory wave and the dominant (DA) follicle of a mid-cycle anovulatory wave (n=6 mares). Follicular fluid levels of progesterone and estradiol were lower (P<0.01) in S follicles than in DO follicles, whereas mean levels of IGF1 were lower (P<0.01) in S and DA follicles than in DO follicles. Relative to DO and DA follicles, S follicles had higher (P≤0.01) follicular fluid levels of miR-145 and miR-378. In Experiment 2, follicular fluid and granulosa cells were aspirated from dominant follicles before (DO) and 24 h after (L) administration of an ovulatory dose of hCG (n=5 mares/group). Relative to DO follicles, L follicles had higher follicular fluid levels of progesterone (P=0.05) and lower granulosa cell levels ofCYP19A1andLHCGR(P<0.005). Levels of miR-21, miR-132, miR-212, and miR-224 were increased (P<0.05) in L follicles; this was associated with reduced expression of the putative miRNA targets,PTEN,RASA1, andSMAD4. These novel results may indicate a physiological involvement of miR-21, miR-145, miR-224, miR-378, miR-132, and miR-212 in the regulation of cell survival, steroidogenesis, and differentiation during follicle selection and ovulation in the monovular ovary.
28
Kim, Soon Ok, Siabhon M. Harris e Diane M. Duffy. "Prostaglandin E2 (EP) Receptors Mediate PGE2-Specific Events in Ovulation and Luteinization Within Primate Ovarian Follicles". Endocrinology 155, n.º 4 (1 de abril de 2014): 1466–75. http://dx.doi.org/10.1210/en.2013-2096.
Texto completo da fonteResumo:
Prostaglandin E2 (PGE2) is a key mediator of ovulation. All 4 PGE2 receptors (EP receptors) are expressed in the primate follicle, but the specific role of each EP receptor in ovulatory events is poorly understood. To examine the ovulatory events mediated via these EP receptors, preovulatory monkey follicles were injected with vehicle, the PG synthesis inhibitor indomethacin, or indomethacin plus PGE2. An ovulatory dose of human chorionic gonadotropin was administered; the injected ovary was collected 48 hours later and serially sectioned. Vehicle-injected follicles showed normal ovulatory events, including follicle rupture, absence of an oocyte, and thickening of the granulosa cell layer. Indomethacin-injected follicles did not rupture and contained oocytes surrounded by unexpanded cumulus; granulosa cell hypertrophy did not occur. Follicles injected with indomethacin plus PGE2 were similar to vehicle-injected ovaries, indicating that PGE2 restored the ovulatory changes inhibited by indomethacin. Additional follicles were injected with indomethacin plus an agonist for each EP receptor. EP1, EP2, and EP4 agonists each promoted aspects of follicle rupture, but no single EP agonist recapitulated normal follicle rupture as seen in follicles injected with either vehicle or indomethacin plus PGE2. Although EP4 agonist-injected follicles contained oocytes in unexpanded cumulus, the absence of oocytes in EP1 agonist- and EP2 agonist-injected follicles suggests that these EP receptors promote cumulus expansion. Surprisingly, the EP3 agonist did not stimulate any of these ovulatory changes, despite the high level of EP3 receptor expression in the monkey follicle. Therefore, agonists and antagonists selective for EP1 and EP2 receptors hold the most promise for control of ovulatory events in women.
29
Greenfield, L. J., J. T. Hackett e J. Linden. "Xenopus oocyte K+ current. I. FSH and adenosine stimulate follicle cell-dependent currents". American Journal of Physiology-Cell Physiology 259, n.º 5 (1 de novembro de 1990): C775—C783. http://dx.doi.org/10.1152/ajpcell.1990.259.5.c775.
Texto completo da fonteResumo:
Ovarian follicles of Xenopus laevis frogs consist of a single large oocyte surrounded by follicle cells attached to the oocyte by gap junctions. Adenosine has been found to activate an outward K+ current in follicles. This response is reduced by microinjection of protein kinase inhibitor (PKI), suggesting that adenosine 3',5'-cyclic monophosphate (cAMP) mediates the response. To investigate this further, we verified previous studies that indicate that several methods of elevating cAMP in follicles activate hyperpolarizing outward currents. The potency of two adenosine analogues to hyperpolarize follicles, 5'-N-ethylcarboxamidoadenosine (NECA) greater than cyclopentyladenosine, is indicative of A2 receptors that are characteristically coupled to adenylyl cyclase. We also report for the first time that another stimulator of adenylyl cyclase, follicle-stimulating hormone (FSH), also induces a hyperpolarizing current in follicles which is carried by K+ and attenuated by injection of PKI. We used a novel procedure to completely remove follicle cells from oocytes. Intact follicles, but not oocytes completely stripped of follicle cells, hyperpolarized in response to FSH, NECA, dibutyryl cAMP, microinjected cAMP, and forskolin, but not to dideoxyforskolin (which does not activate adenylyl cyclase). Injection of the catalytic subunit of cAMP-dependent protein kinase (which is too large to traverse gap junctions) into oocytes of intact follicles failed to activate a K+ current. These data suggest that FSH and adenosine hyperpolarize follicles by stimulating adenylyl cyclase and that cAMP-dependent protein kinase must be activated on both sides of follicle cell-oocyte gap junctions to elicit a hyperpolarizing K+ current.
30
Fortune, Joanne E., Ming Y. Yang e Wanzirai Muruvi. "In vitro and in vivo regulation of follicular formation and activation in cattle". Reproduction, Fertility and Development 23, n.º 1 (2011): 15. http://dx.doi.org/10.1071/rd10250.
Texto completo da fonteResumo:
The establishment of a stockpile of non-growing, primordial follicles and its gradual depletion through activation of primordial follicles are essential processes for female fertility. However, the mechanisms that regulate follicle formation, the activation of primordial follicles to begin growth and the primary-to-secondary follicle transition are poorly understood, especially in domestic animals and primates. The authors’ laboratory is engaged in studying early stages of follicular development in cattle and this review summarises the progress to date. Bovine follicles begin to form in fetal ovaries around the beginning of the second trimester of pregnancy (about Day 90), but the first activated, primary follicles do not appear until after Day 140. Bovine fetal ovaries produce steroids and production is highest during the first trimester. In vitro, oestradiol and progesterone inhibit follicle formation and acquisition by newly formed follicles of the capacity to activate. Meiotic arrest of the oocyte in the diplotene stage of first prophase does not occur until after follicle formation and is correlated with acquisition of the capacity to activate. This may explain the gap between follicle formation and appearance of the first activated follicles. Once capacity to activate has been acquired, it seems likely that activation in vivo is controlled by the balance between stimulators and inhibitors of activation. Insulin and kit ligand stimulate and anti-Müllerian hormone (AMH) inhibits activation in vitro. Few bovine follicles transition from the primary to the secondary stage in vitro, but this transition is increased by medium supplements, testosterone and vascular endothelial growth factor (VEGF).
31
Antos, Piotr A., Anna Hrabia, Anna Gdula e Andrzej Sechman. "Apoptosis in chicken ovarian follicles following in vitro exposure to TCDD, PCB 126 and PCB 153". Annals of Animal Science 17, n.º 3 (26 de julho de 2017): 787–98. http://dx.doi.org/10.1515/aoas-2016-0087.
Texto completo da fonteResumo:
Abstract The study was conducted in order to compare the in vitro effect of 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD), 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126) and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) on the number of apoptotic cells and the activity of caspase-3 in chicken ovarian follicles. The ovarian stroma, white (WF) and yellowish (YF) prehierarchical follicles and fragments of the theca and granulosa layers of the 3 largest preovulatory follicles (F3-F1) were in vitro exposed to TCDD (10 nM), PCB 126 (10 nM) and PCB 153 (10 μM) for 24 h. After incubation the number of apoptotic cells and caspase-3 activity were determined by TUNEL method and fluorometric assay, respectively. PCB 126 and PCB 153 increased the number of apoptotic cells in the ovarian stroma while TCDD and PCB 126 elevated it in the WF follicles. Under the control conditions, caspase-3 activity steadily increased along with maturation of the follicles, reaching the highest level in the theca layer of the F1 follicle. The activity of this enzyme in the granulosa layer of F3-F1 follicles was on average 60% lower in comparison to the stroma. Exposure to TCDD elevated caspase-3 activity in prehierarchical follicles and in the granulosa layer of F2 and F1 preovulatory follicles. On the contrary, PCB 126 exerted a suppressive effect on caspase-3 activity in the WF follicles and the granulosa layer of the F2 follicle, and PCB 153 in the theca layer of F2 and F1 and the granulosa layer of the F3 follicle. In conclusion, the results indicate that TCDD and PCBs affect apoptosis in chicken ovarian follicles and in consequence may disrupt follicle development.
32
Emmen, Judith M. A., John F. Couse, Susan A. Elmore, Mariana M. Yates, Grace E. Kissling e Kenneth S. Korach. "In Vitro Growth and Ovulation of Follicles from Ovaries of Estrogen Receptor (ER)α and ERβ Null Mice Indicate a Role for ERβ in Follicular Maturation". Endocrinology 146, n.º 6 (1 de junho de 2005): 2817–26. http://dx.doi.org/10.1210/en.2004-1108.
Texto completo da fonteResumo:
Abstract Both estrogen receptor (ER) α and β are expressed within the ovary and lack of either of these receptors affects ovarian function. In this study, the role of ERα and ERβ in folliculogenesis and ovulation was further analyzed. Evaluation of ovarian follicle populations in wild-type and ERβ knockout (βERKO) ovaries revealed reduced late antral growth and ovulatory capacity of βERKO follicles, indicated by reduced numbers of large antral follicles and corpora lutea and increased atresia of large antral follicles. An in vitro culture system was used to study growth, rupture, and luteinization of wild-type, ERα knockout (αERKO) and βERKO ovarian follicles. αERKO follicles exhibited wild-type-like growth and ovulation rates but an increased capacity to synthesize estradiol. In contrast, βERKO follicles showed a significant lack of progression from early antral to large antral stage, decreased estradiol production, and reduced ovulation. Expression patterns of several genes involved in follicle maturation and ovulation were analyzed in follicles grown in vitro. Ar, Pgr, and Has2 mRNA expression levels were the same among the three genotypes. However, βERKO follicles showed reduced expression of Cyp19 mRNA during follicle maturation and reduced Lhcgr and Ptgs2 mRNA expression after human chorionic gonadotropin stimulus. Luteinization occurs normally in αERKO and βERKO follicles, shown by increased progesterone secretion and increased cdkn1b mRNA expression after human chorionic gonadotropin. Collectively, these data indicate that ERβ, but not ERα, plays a direct role in folliculogenesis. ERβ appears to facilitate follicle maturation from the early antral to the preovulatory stage.
33
Durlinger, Alexandra L. L., Maria J. G. Gruijters, Piet Kramer, Bas Karels, T. Rajendra Kumar, Martin M. Matzuk, Ursula M. Rose et al. "Anti-Müllerian Hormone Attenuates the Effects of FSH on Follicle Development in the Mouse Ovary". Endocrinology 142, n.º 11 (1 de novembro de 2001): 4891–99. http://dx.doi.org/10.1210/endo.142.11.8486.
Texto completo da fonteResumo:
Abstract Although ovarian follicle growth is under the influence of many growth factors and hormones of which FSH remains one of the most prominent regulators. Therefore, factors affecting the sensitivity of ovarian follicles to FSH are also important for follicle growth. The aim of the present study was to investigate whether anti-Müllerian hormone (AMH) has an inhibitory effect on follicle growth by decreasing the sensitivity of ovarian follicles to FSH. Furthermore, the combined action of AMH and FSH on ovarian follicle development was examined. Three different experiments were performed. Using an in vitro follicle culture system it was shown that FSH-stimulated preantral follicle growth is attenuated in the presence of AMH. This observation was confirmed by an in vivo experiment showing that in immature AMH-deficient females, more follicles start to grow under the influence of exogenous FSH than in their wild-type littermates. In a third experiment, examination of the follicle population of 4-month-old wild-type, FSHβ-, AMH-, and AMH-/FSHβ-deficient females revealed that loss of FSH expression has no impact on the number of primordial and preantral follicles, but the loss of inhibitory action of AMH on the recruitment of primordial follicles in AMH-deficient mice is increased in the absence of FSH. In conclusion, these studies show that AMH inhibits FSH-stimulated follicle growth in the mouse, suggesting that AMH is one of the factors determining the sensitivity of ovarian follicles for FSH and that AMH is a dominant regulator of early follicle growth.
34
Kezele, Phillip, e Michael K. Skinner. "Regulation of Ovarian Primordial Follicle Assembly and Development by Estrogen and Progesterone: Endocrine Model of Follicle Assembly". Endocrinology 144, n.º 8 (1 de agosto de 2003): 3329–37. http://dx.doi.org/10.1210/en.2002-0131.
Texto completo da fonteResumo:
Abstract The assembly of the developmentally arrested primordial follicle and the subsequent transition of the primordial follicle to the primary follicle are critical processes in normal ovarian physiology that remain to be elucidated. Ovarian follicles do not proliferate and the primordial follicles present in the neonate represent the total number of gametes available to a female throughout her reproductive life. The primordial follicles are oocytes surrounded by less differentiated squamous granulosa cells and are derived from oocyte nests, and primary follicles are oocytes surrounded by a single layer of cuboidal granulosa cells that have initiated follicle development. Abnormalities in primordial follicle assembly, arrest, and development (i.e. primordial to primary follicle transition) can cause pathological conditions such as premature ovarian failure. In this study newborn rat ovaries were cultured for 7 d. The rate of primordial follicle assembly in vivo was identical with the rate in vitro. Interestingly, the rate of primordial follicle transition to the primary follicle was found to be 3 times greater in culture. This abnormal rate of primary follicle development in culture suggests the primordial follicle does not arrest in development as observed in vivo. To investigate this phenomena newborn rat ovaries were cultured in the presence of progesterone, estradiol or calf serum. Estradiol, progesterone, or calf serum significantly reduced the level of initial primordial to primary follicle transition. Approximately 60% of follicles make the primordial to primary follicle transition in control ovaries and about 30% in treated ovaries. Steroids and calf serum had no effect on the primordial to primary follicle transition in ovaries collected and cultured from postnatal 4-d-old rats, suggesting the effects observed are restricted to the initial wave of primordial to primary follicle transition. Interestingly, progesterone was also found to significantly reduce the rate of primordial follicle assembly. All viable oocytes assembled into primordial follicles in control ovaries and approximately 40% remained unassembled in progesterone-treated ovaries. Progesterone was also found to reduce primordial follicle assembly in vivo with 10% of the total follicles remaining unassembled in progesterone injected neonatal animals. Analysis of cellular apoptosis demonstrated that progesterone inhibited the coordinated oocyte apoptosis required for primordial follicle assembly. The hypothesis developed is that high levels of maternal and fetal steroids prevent premature primordial follicle assembly and primordial to primary follicle transition in the embryo. After birth steroid levels fall dramatically and the primordial follicles are free to assemble and initiate development. These observations suggest a novel role for steroids and the maternal-fetal endocrine unit in the control of ovarian primordial follicle assembly and early follicular development.
35
McGee, Elizabeth A., e Aaron J. W. Hsueh. "Initial and Cyclic Recruitment of Ovarian Follicles*". Endocrine Reviews 21, n.º 2 (1 de abril de 2000): 200–214. http://dx.doi.org/10.1210/edrv.21.2.0394.
Texto completo da fonteResumo:
Abstract Mammalian ovaries consist of follicles as basic functional units. The total number of ovarian follicles is determined early in life, and the depletion of this pool leads to reproductive senescence. Each follicle develops to either ovulate or, more likely, to undergo degeneration. The dynamics of ovarian follicle development have interested endocrinologists and developmental biologists for many years. With the advent of assisted reproductive techniques in humans, the possibility of regulating follicle development in vivo and in vitro has gained clinical relevance. In this review, we focus upon key branching points during the development of ovarian follicles as well as factors involved in determining the eventual destiny of individual follicles. We discuss inconsistencies in the literature regarding the definitions of follicle recruitment and selection and propose to name the two major steps of follicle development as initial and cyclic recruitment, respectively. Because some of these disparities have arisen due to differences in the animal systems studied, we also compare the development of the ovarian follicles of both humans and rats. We also review the status of knowledge of several puzzling clinical issues that may provide important clues toward unlocking the mechanisms of follicle development.
36
Ferguson, M. B., B. A. McGregor e R. Behrendt. "Relationships between skin follicle characteristics and fibre properties of Suri and Huacaya alpacas and Peppin Merino sheep". Animal Production Science 52, n.º 7 (2012): 442. http://dx.doi.org/10.1071/an11233.
Texto completo da fonteResumo:
We aimed to quantify the number, type and arrangement of skin follicles in Huacaya and Suri alpaca skin and correlate their follicle characteristics with fibre traits of harvested fibre and compared these relationships with those of Merino sheep. Fibre and skin samples were collected from the mid-side of 12 Huacaya alpacas, 24 Suri alpacas and 10 Merino sheep. The mean fibre diameter (MFD ± s.e.) of the Huacaya and Suri were: 35.5 ± 0.9 and 28.3 ± 1.0 μm, respectively. The follicle groups found for alpacas were very different from the normal trio of primary follicles found in sheep and goats. The follicle group of the alpacas consisted of a single primary follicle surrounded by a variable number of secondary follicles. The mean ± s.e. primary follicle density was 3.1 ± 0.3 and 2.7 ± 0.1 follicles/mm2 for Huacaya and Suri, respectively. The mean ± s.e. secondary follicle density (SFD) was 13.7 ± 1.2 and 17.5 ± 0.6 follicles/mm2 for Huacaya and Suri, respectively. The mean ± s.e. ratio of secondary to primary follicles (S/P ratio) was 5.1 ± 0.5 for the Huacaya and 7.3 ± 0.2 for the Suri alpacas. The sheep had higher S/P ratios and SFD, lower MFD and produced significantly heavier fleeces. The key correlations found between traits in alpacas include a negative correlation between SFD and MFD (r = –0.71, P = 0.001) and a negative correlation between S/P ratio and MFD (r = –0.44, P = 0.003) and a positive correlation between S/P ratio and total follicle density (r = 0.38, P = 0.010). The study revealed that important relationships exist between alpaca skin follicle characteristics and fibre characteristics. It was the number of secondary follicles in a group that imparts density and a corresponding reduced MFD.
37
Leitão, Cintia Camurça Fernandes, José Jackson Nascimento Costa, Márcia Viviane Alves Saraiva, Valdevane Rocha Araújo, José Ricardo Figueiredo, Robert van den Hurk e José Roberto Viana Silva. "Goat ovarian follicles express different levels of mRNA for inhibin-ßA subunit and activin-A stimulates secondary follicle growth in vitro". Ciência Rural 43, n.º 1 (22 de novembro de 2012): 107–13. http://dx.doi.org/10.1590/s0103-84782012005000140.
Texto completo da fonteResumo:
This study investigated the levels of messenger ribonucleic acids (mRNA) for inhibin-ßA subunit in goat primordial, primary and secondary follicles, as well as in cumulus-oocyte complexes (COCs) and mural granulosa / theca cells of antral follicles. The effects of activin-A (100ng mL-1) and/or follicle stimulating hormone (FSH, 50ng mL-1) on growth and expression of mRNA for activin-A and FSH receptor (FSH-R) in secondary follicles cultured for six days were evaluated. The data showed that the expression of inhibin-ßA is lower in secondary follicles than in primary follicles and is higher in large antral follicles than in small antral follicles. After culture, activin-A and/or FSH promoted growth of secondary follicles, while FSH increased the levels of mRNA for inhibin-ßA, and activin-A increased the levels of FSH-R mRNA. In conclusion, mRNA for inhibin-ßA is expressed at different levels in pre-antral and antral follicles and activin-A acts as a stimulator of the FSH-R expression in goat follicles. On its turn, the expression of inhibin-ßA is stimulated by FSH, which together with activin-A promotes secondary follicle growth in-vitro.
38
Dipaz-Berrocal, D. J., G. Rojas, C. Mamani, J. R. Figueiredo e E. Mellisho. "87 Population estimate and morphology of ovarian preantral follicles in fetal and adult alpacas (Vicugna pacos)". Reproduction, Fertility and Development 33, n.º 2 (2021): 151. http://dx.doi.org/10.1071/rdv33n2ab87.
Texto completo da fonteResumo:
Preantral follicles are the largest ovarian follicle population and represent an important source of potentially competent oocytes. During the lifespan of the female this large population becomes atretic during their growth. In alpacas, there are few studies that estimate the number of preantral follicles. Therefore, the objective of the present study was to compare the population and morphology of preantral follicles in the ovaries of fetal and adult alpacas. Ovaries from alpacas in fetal (fetus during the last third of gestation, n=5) and adult stage (3–4 years, n=5) were collected at a local slaughterhouse. The whole ovaries were individually fixed overnight at room temperature, and later dehydrated in alcohol, cleared with xylene, and embedded in paraffin. Tissue were sectioned at 7μm with a rotating microtome. Then, sections were processed and stained with periodic acid Schiff and haematoxylin. Preantral follicles were classified for their development stage as primordial, transitional, primary, or secondary, according to the layer number and form of granulosa cells. Estimation of the number of preantral follicles was made by counting all follicles in each histological section. Only follicles in which the oocyte nucleus was visible were counted. In addition, for each follicle category (n=30 per group), oocyte and follicle diameters were measured using Motic Images Plus 2.0 software. The population estimate and follicular diameter were compared using Kruskal–Wallis test with significance set at P ≤ 0.05 using SPSS v.2 2 software (IBM Corp.). A total of 2174 histologic sections were analysed. The results showed a higher (P=0.045) number of preantral follicles (80 516.1±3623.9) for fetal alpacas compared with adult alpacas (67 870.8±2267.4). Also, primordial follicles population (31 543.4±2690) and morphologically normal follicles (98.2%) were higher (P=0.04) in fetus compared with those in the adult stage (2244.7±355.37; 76.35%) respectively. On the contrary, the diameters of primordial, transitional, and primary follicles (45.34±3.76; 52.38±6.22; 59.79±5.22µm) from adult alpaca were greater (P=0.04) than those of fetal preantral follicles (33.305±7.2; 36.715±3; 77.985±15.8µm). In conclusion, the preantral follicle population declines dramatically in adult alpaca and animals of this age show an increased percentage of degenerate primordial follicles.
39
Dipaz-Berrocal, D. J., G. Rojas, C. Mamani, J. R. Figueiredo e E. Mellisho. "87 Population estimate and morphology of ovarian preantral follicles in fetal and adult alpacas (Vicugna pacos)". Reproduction, Fertility and Development 33, n.º 2 (2021): 151. http://dx.doi.org/10.1071/rdv33n2ab87.
Texto completo da fonteResumo:
Preantral follicles are the largest ovarian follicle population and represent an important source of potentially competent oocytes. During the lifespan of the female this large population becomes atretic during their growth. In alpacas, there are few studies that estimate the number of preantral follicles. Therefore, the objective of the present study was to compare the population and morphology of preantral follicles in the ovaries of fetal and adult alpacas. Ovaries from alpacas in fetal (fetus during the last third of gestation, n=5) and adult stage (3–4 years, n=5) were collected at a local slaughterhouse. The whole ovaries were individually fixed overnight at room temperature, and later dehydrated in alcohol, cleared with xylene, and embedded in paraffin. Tissue were sectioned at 7μm with a rotating microtome. Then, sections were processed and stained with periodic acid Schiff and haematoxylin. Preantral follicles were classified for their development stage as primordial, transitional, primary, or secondary, according to the layer number and form of granulosa cells. Estimation of the number of preantral follicles was made by counting all follicles in each histological section. Only follicles in which the oocyte nucleus was visible were counted. In addition, for each follicle category (n=30 per group), oocyte and follicle diameters were measured using Motic Images Plus 2.0 software. The population estimate and follicular diameter were compared using Kruskal–Wallis test with significance set at P ≤ 0.05 using SPSS v.2 2 software (IBM Corp.). A total of 2174 histologic sections were analysed. The results showed a higher (P=0.045) number of preantral follicles (80 516.1±3623.9) for fetal alpacas compared with adult alpacas (67 870.8±2267.4). Also, primordial follicles population (31 543.4±2690) and morphologically normal follicles (98.2%) were higher (P=0.04) in fetus compared with those in the adult stage (2244.7±355.37; 76.35%) respectively. On the contrary, the diameters of primordial, transitional, and primary follicles (45.34±3.76; 52.38±6.22; 59.79±5.22µm) from adult alpaca were greater (P=0.04) than those of fetal preantral follicles (33.305±7.2; 36.715±3; 77.985±15.8µm). In conclusion, the preantral follicle population declines dramatically in adult alpaca and animals of this age show an increased percentage of degenerate primordial follicles.
40
Ruoss, Chantelle, Amanda Tadros, Tim O'Shea, Jim McFarlane e Ghanim Almahbobi. "Ovarian follicle development in Booroola sheep exhibiting impaired bone morphogenetic protein signalling pathway". REPRODUCTION 138, n.º 4 (outubro de 2009): 689–96. http://dx.doi.org/10.1530/rep-09-0190.
Texto completo da fonteResumo:
The role of bone morphogenetic proteins (BMPs) in the regulation of ovarian function has been extensively investigated but the mechanism of regulation is not well understood. The aim of this study was to investigate the effect of mutation in the BMP receptor in Booroola sheep on the number of primordial follicles and rate of follicle recruitment in comparison with that in normal merino sheep in vivo. Whole sheep ovaries at the time of birth, 1.5 and 5 years old were collected and processed for the follicle quantification, using computerised stereological methods and statistical analyses. At birth, the total number of primordial follicles in Booroola sheep was significantly lower than in merino sheep. At 1.5 and 5 years, a reversed pattern in favour of Booroola ewes was seen with significantly more primordial follicles than merino. In parallel, the rate of primordial follicle recruitment to developing cohort was substantially lower in Booroola ewes with only 51 and 66% of primordial follicle consumption at 1.5 and 5 years respectively compared to 92 and 97% in merino ewes. On other hand, the mean numbers of developing primary follicles were smaller in Booroola sheep at the time of birth, yet, Booroola ewes possess more primary follicles than merino at 1.5 years. These findings suggest that attenuation of the intraovarian signalling pathway of BMPs may in fact be a successful means of rationalising follicle consumption, preventing unnecessary loss of follicles from the initial primordial follicle pool, hence increasing reproductive longevity and fertility.
41
Barroso, P. A. A., L. R. F. M. Paulino, B. R. Silva, G. L. Vasconcelos, D. S. Gomes, M. F. Lima Neto, A. W. B. Silva et al. "Effects of dexamethasone on growth, viability and ultrastructure of bovine secondary follicles cultured in vitro". Zygote 28, n.º 6 (27 de agosto de 2020): 504–10. http://dx.doi.org/10.1017/s0967199420000416.
Texto completo da fonteResumo:
SummaryThis study aimed to evaluate the effects of dexamethasone on development, viability, antrum formation and ultrastructural integrity of bovine secondary follicles cultured in vitro for 18 days. Bovine ovaries were obtained from slaughterhouses and secondary follicles of ~150–200 µm diameter were isolated and cultured in the laboratory in TCM-199+ alone or supplemented with different concentrations of dexamethasone (1, 10, 100 and 1000 ng/ml). Follicle viability was evaluated after the culture period, using calcein-AM (viable) and ethidium homodimer (nonviable). Follicle diameters and antrum formation were evaluated at days 0, 6, 12 and 18. Before or after in vitro culture, follicles were fixed for histological and ultrastructural analysis. Follicle diameters were evaluated using analysis of variance and Kruskal–Wallis test, while chi-squared test was used to evaluate the percentage of viable follicles and antrum formation (P < 0.05). Follicles cultured for 6 days with all treatments increased their diameters significantly, but there was no significant difference between treatments at the end of the culture period. In vitro cultured follicles showed antral cavity formation at the end of the culture period, but no influence of dexamethasone was seen. Ultrastructural analysis showed that follicles cultured with dexamethasone (1, 10, 100 and 1000 ng/ml) had well preserved granulosa cells. However, oocytes from follicles cultured with 10, 100 or 1000 ng/ml dexamethasone showed signs of degeneration. It can be concluded that follicles cultured in vitro in the presence of dexamethasone demonstrated continuous in vitro growth, but oocytes from follicles cultured with 10, 100 or 1000 ng/ml dexamethasone had poor ultrastructure.
42
Starcher, Barry, Ronnie L. Aycock e Charles H. Hill. "Multiple Roles for Elastic Fibers in the Skin". Journal of Histochemistry & Cytochemistry 53, n.º 4 (abril de 2005): 431–43. http://dx.doi.org/10.1369/jhc.4a6484.2005.
Texto completo da fonteResumo:
Dermal elastic fibers are believed to have a primary role in providing elastic stretch and recoil to the skin. Here we compare the structural arrangement of dermal elastic fibers of chick skin and different animal species. Most elastic fibers in chick skin are derived from cells that line the feather follicle and/or smooth muscle that connects the pterial and apterial muscle bundles to feather follicles. Elastic fibers in the dermis of animals with single, primary hair follicles are derived from cells lining the hair follicle or from the ends of the pili muscle, which anchors the muscle to the matrix or to the hair follicle. Each follicle is interconnected with elastic fibers. Follicles of animals with primary and secondary (wool) hair follicles are also interconnected by elastic fibers, yet only the elastic fibers derived from the primary follicle are connected to each primary follicle. Only the primary hair follicles are connected to the pili muscle. Human skin, but not the skin of other primates, is significantly different from other animals with respect to elastic fiber organization and probably cell of origin. The data suggest that the primary role for elastic fibers in animals, with the possible exception of humans, is movement and/or placement of feathers or hair.
43
Edwards, J. E. Hocking. "Reduction in wool follicles prior to birth in Merino sheep". Reproduction, Fertility and Development 11, n.º 5 (1999): 229. http://dx.doi.org/10.1071/rd99049.
Texto completo da fonteResumo:
This study was undertaken to identify whether all secondary follicles that are initiated are present at birth in the Merino fetus, and if not, when does net initiation of secondary follicles cease. Skin was sampled from fetal lambs at 36, 26 and 16 days before the estimated date of parturition and from lambs at birth and 2, 4, 6, 8 and 13 weeks after birth. The ratio of secondary to primary follicles (S/P) reached a maximum 16 days before birth and was significantly lower at birth (P<0.002) and at all postnatal ages (P<0.05). There was no difference between S/P at birth and S/P at later ages. Postnatal primary follicle density, secondary follicle density and the percentage of fibre-producing follicles followed similar patterns to those reported by others. This is the first conclusive demonstration that secondary follicle initiation is completed several weeks prior to birth and that there are less secondary follicles at birth than at 134 days of gestation.
44
Armstrong, D. G. "Ornithine decarboxylase activity in small ovarian follicles from the laying hen (Gallus domesticus): a comparison of follicles from several regions of the ovary". Journal of Endocrinology 112, n.º 2 (fevereiro de 1987): 183–87. http://dx.doi.org/10.1677/joe.0.1120183.
Texto completo da fonteResumo:
ABSTRACT Small non-atretic follicles (1·5–250 mg) were collected from four distinct areas of the ovary of the laying hen. These were as follows: (1) the stalks of the two largest preovulatory follicles; (2) the stalks of the third largest preovulatory follicle; (3) the stalks of the fourth and fifth largest preovulatory follicle and (4) zona parenchymatosa. There was an increase in the proportion of small follicles in the size range 1·5–10 mg collected from the stalks of the large yellow yolky preovulatory follicles approaching ovulation, with a corresponding decrease in the number of small follicles in the size group 10–250 mg. In addition, the ornithine decarboxylase activity in follicles collected from regions 1 and 2 was significantly greater than that in small follicles collected from region 4. Since the level of ornithine decarboxylase activity is critically dependent on the degree of hormonal stimulation and growth rate of the tissue, it is suggested, on the basis of the differences in their ornithine decarboxylase activity, that small follicles located on the stalks of the large yolky preovulatory follicles are stimulated by trophic hormones and growth factors to a greater degree than similarly sized follicles located elsewhere in the ovary. It is proposed that this increased stimulation may increase the chances of these small follicles being recruited into the hierarchy. J. Endocr. (1987) 112, 183–187
45
Jurgens, Isabella M., Friederike Baumgaertner, Sarah R. Underdahl, Jennifer L. Hurlbert, Kerri A. Bochantin, Kevin K. Sedivec, James D. Kirsch et al. "PS-6 Nutrition During Early Pregnancy Impacts Offspring Ovarian Characteristics". Journal of Animal Science 100, Supplement_4 (22 de outubro de 2022): 19. http://dx.doi.org/10.1093/jas/skac313.027.
Texto completo da fonteResumo:
Abstract During early pregnancy offspring are directly exposed to nutrients consumed by their mother, and the development of their own reproductive tract is underway. The objective of this research was to determine how characteristics of offspring ovaries were affected by different maternal rates of gain during the first trimester of gestation in beef heifers. Before breeding antral follicle counts were determined via ultrasound. Beginning at breeding Angus heifers were managed to achieve one of two rates of gain: low (0.20 kg/d, n = 8; LG) or moderate (0.75 kg/d, n = 8; MG) for the first trimester of pregnancy, after which they were managed as a single group through F1 calving. Calves remained with their dams until weaning and were managed as a single group through breeding. These F1 heifer calves were then synchronized and bred to a single sire using female sexed semen. On the 84th day of gestation (approximate heifer age 17 months) ovaries were removed from the reproductive tract, weighed, and visible antral follicles were counted. Cross-sections from each ovary were post-fixed and embedded in paraffin, then each of 3 sections (5 µm, with 10 sections between to avoid counting follicles more than once) were stained with Hematoxylin and Eosin for histological evaluation. Number of primordial, primary, secondary, and antral follicles were determined for each section. Data were analyzed using the GLM procedure of SAS with significance declared at P ≤ 0.05. The CORR procedure of SAS was used to calculate correlations between pre-breeding antral follicle counts, surface follicle counts, and histological follicle counts. Though no differences were observed in number of visible follicles (P = 0.45), the corpus luteum (CL) was heavier (P = 0.03) and average ovarian length was greater (P = 0.04) in offspring from LG dams compared with those from MG dams. No differences were observed in the number of primordial, primary, secondary, or antral follicles between treatments (P ≤ 0.18). There was a correlation between the number of histological follicles and surface follicles (r = 0.73; P = 0.002) and pre-breeding antral follicles and surface follicles (r = 0.60; P = 0.014), but there was no correlation between pre-breeding antral follicles and histological follicles (P = 0.10). Heavier CLs have a positive correlation with amount of progesterone released, which is essential for pregnancy maintenance. Longer lengths of ovaries suggest more area for follicles to develop, which is indicative of future reproductive success. Data corroborates previous reports regarding positive correlations between antral follicle count determined via ultrasound and counts of surface follicles on extracted ovaries. These findings demonstrate that nutrition during the first trimester of gestation impacts offspring reproductive tract development.
46
Fowler, Paul A., e Norah Spears. "The cultured rodent follicle as a model for investigations of gonadotrophin surge-attenuating factor (GnSAF) production". Reproduction 127, n.º 6 (junho de 2004): 679–88. http://dx.doi.org/10.1530/rep.1.00141.
Texto completo da fonteResumo:
Gonadotrophin surge-attenuating factor (GnSAF) bioactivity (the suppression of GnRH-induced but not basal LH and FSH secretion from pituitary gonadotrophs) is produced by granulosa cells in vitro. Previous studies to investigate this bioactivity used dispersed granulosa cells which lack some cell types and the structural components of the follicle in vivo. The aim of this study, therefore, was to investigate whether intact rodent follicle culture was a suitable model for the study of the production of GnSAF bioactivity, allowing GnSAF to be investigated in a more physiologically realistic environment while still retaining culture conditions from which, as with granulosa cell cultures, extraneous factors can be excluded. Follicles from 16-day-old rats and 21-day-old mice were cultured for 3–6 days in the presence or absence of FSH and/or LH. The follicle-conditioned medium, and matching samples of unconditioned culture medium were added to our established rat pituitary monolayer GnSAF bioassay. Both mouse and rat intact follicles produced GnSAF bioactivity, reducing GnRH-induced LH secretion significantly. GnSAF output from the mouse follicles was highest during days 1–3 of culture, when follicles were at an early antral stage of development, and fell on days 4–6 as the follicles grew to the mid antral stage. While the stimulatory effects of FSH on rat follicle GnSAF secretion was dose-dependent, LH alone did not increase GnSAF production. An antibody against human GnSAF blocked GnSAF bioactivity produced by rat follicles, and recognised proteins within the expected pI and molecular weight range for GnSAF in two-dimensional gels of rat follicle-conditioned medium, showing a good homology between rodent and human GnSAF proteins. In conclusion, the release of GnSAF bioactivity is principally from small follicles stimulated by FSH. Therefore, intact rodent follicle culture systems offer an excellent model for the investigation of factors controlling GnSAF production under relatively physiological conditions.
47
Yuan, Wei, e Linda C. Giudice. "Programmed Cell Death in Human Ovary Is a Function of Follicle and Corpus Luteum Status*". Journal of Clinical Endocrinology & Metabolism 82, n.º 9 (1 de setembro de 1997): 3148–55. http://dx.doi.org/10.1210/jcem.82.9.4191.
Texto completo da fonteResumo:
Abstract Although extensive investigation on follicular apoptosis (programmed cell death) has been conducted in the infraprimate ovary, there is little information regarding apoptosis and its relationship to follicular status in the human. In this study, apoptosis was investigated in 116 human ovarian follicles (primordial to dominant) and 5 corpora lutea from a total of 27 premenopausal women. Follicles and corpora lutea were evaluated for the presence of DNA fragmentation, characteristic of apoptosis, by two methods: in situ hybridization using 3′ end-labeling of DNA with digoxigenin-labeled nucleotides and subsequent digoxigenin antibody and peroxidase staining, and/or biochemical analysis of low molecular weight DNA laddering. Follicle functional status was evaluated by determining follicle sizes and follicular fluid androgen/estrogen (A/E) ratios. No apoptosis was observed in 67 primordial, primary, or secondary follicles. Positive staining for DNA fragmentation was found in a few granulosa cells in 0.1- to 2-mm follicles, whereas abundant staining in granulosa was detected in 2.1- to 9.9-mm follicles. In contrast, no DNA fragmentation was detected in dominant follicles (10–16 mm). The frequency of apoptosis in follicles was calculated to be 37% in 0.1- to 2-mm follicles, 50% in 2.1- to 5-mm follicles, and 27% in 5.1- to 9.9-mm follicles. Abundant low molecular weight DNA laddering was only found in androgen-dominant follicles and not in estrogen-dominant follicles. Positive staining for DNA fragmentation and low molecular weight DNA laddering were observed in degenerating but not healthy-appearing corpora lutea. In the former, DNA fragmentation was found primarily in large luteal cells. These data suggest that follicular atresia in human ovary results from normal programmed cell death and primarily occurs in the granulosa cell layers of the early antral and <10-mm antral follicles primarily. Furthermore, because apoptosis occurs as early as the 200-mm stage, follicle selection may begin as early as the initial formation of the antrum. The results also suggest that degeneration of the corpus luteum occurs by apoptotic mechanisms.
48
Rajabzadeh, Alireza, Fatemeh Jahanpeyma, Ali Talebi, Faezeh Moradi e Hussein Eimani. "Fibrin Scaffold Incorporating Platelet Lysate Enhance Follicle Survival and Angiogenesis in Cryopreserved Preantral Follicle Transplantation". Galen Medical Journal 9 (8 de julho de 2020): 1558. http://dx.doi.org/10.31661/gmj.v9i0.1558.
Texto completo da fonteResumo:
Background: Transplantation of cryopreserved follicles can be regarded as a promising strategy for preserving fertility in cancer patients under chemotherapy and radiotherapy by reducing the risk of cancer recurrence. The present study aimed to evaluate whether fibrin hydrogel supplemented with platelet lysate (PL) could be applied to enhance follicular survival, growth, and angiogenesis in cryopreserved preantral follicle grafts. Materials and Methods: Preantral follicles were extracted from 15 four-week-old NMRI mice, cryopreserved by cryotop method, and encapsulated in fibrin-platelet lysate for subsequent heterotopic (subcutaneous) auto-transplantation into the neck. Transplants were assessed in three groups including fresh follicles in fibrin-15%PL, cryopreserved follicles in fibrin-15%PL, and cryopreserved follicles in fibrin-0% PL. Two weeks after transplantation, histological, and immunohistochemistry (CD31) analysis were applied to evaluate follicle morphology, survival rate, and vascular formation, respectively. Results: Based on the results, fibrin-15% PL significantly increased neovascularization and survival rate (SR) both in cryopreserved (SR=66.96%) and fresh follicle (SR=90.8%) grafts, compared to PL-less fibrin cryopreserved transplants (SR=28.46%). The grafts supplemented with PL included a significantly higher percentage of preantral and antral follicles. Also, no significant difference was observed in the percentage of preantral follicles between cryopreserved and fresh grafts of fibrin-15% PL. However, a significantly lower (P=0.03) percentage of follicles (23.37%) increased to the antral stage in cryopreserved grafts of fibrin-15%PL, compared to fresh grafts (35.01%). Conclusion: The findings demonstrated that fibrin-PL matrix could be a promising strategy to improve cryopreserved follicle transplantation and preserve fertility in cancer patients at the risk of ovarian failure. [GMJ.2020;9:e1558]
49
Dole, Gretchen, Eric E. Nilsson e Michael K. Skinner. "Glial-derived neurotrophic factor promotes ovarian primordial follicle development and cell–cell interactions during folliculogenesis". REPRODUCTION 135, n.º 5 (maio de 2008): 671–82. http://dx.doi.org/10.1530/rep-07-0405.
Texto completo da fonteResumo:
Female fertility is determined in part by the size and development of the primordial follicle pool. The current study investigates the role of glial cell-line-derived neurotrophic factor (GDNF) in the regulation of primordial follicle development in the ovary. Ovaries from 4-day-old female rat pups were maintained in organ culture for 10 days in the absence (control) or presence of GDNF or kit ligand (KL)/stem cell factor. Ovaries treated with GDNF contained a significant increase in developing follicles, similar to that observed with KL treatment previously shown to promote follicle development. The actions of GDNF on the ovarian transcriptome were investigated with a microarray analysis. Immunohistochemical studies demonstrated that GDNF is localized to oocyte cytoplasm in follicles of all developmental stages, as well as to cumulus granulosa cells and theca cells in antral follicles. GDNF receptor α1 (GFRα1) staining was localized to oocyte cytoplasm of primordial and primary follicles, and at reduced levels in the oocytes of antral follicles. GFRα1 was present in mural granulosa cells of antral follicles, theca cells, and ovarian surface epithelium. The localization studies were confirmed with molecular analysis. Microarray analysis was used to identify changes in the ovarian transcriptome and further elucidate the signaling network regulating early follicle development. Observations indicate that GDNF promotes primordial follicle development and mediates autocrine and paracrine cell–cell interactions required during folliculogenesis. In contrast to the testis, ovarian GDNF is predominantly produced by germ cells (oocytes) rather than somatic cells.
50
Costermans, N. G. J., J. Keijer, E. M. van Schothorst, B. Kemp, S. Keshtkar, A. Bunschoten, N. M. Soede e K. J. Teerds. "In ovaries with high or low variation in follicle size, granulosa cells of antral follicles exhibit distinct size-related processes". Molecular Human Reproduction 25, n.º 10 (19 de julho de 2019): 614–24. http://dx.doi.org/10.1093/molehr/gaz042.
Texto completo da fonteResumo:
Abstract Antral follicle size might be a valuable additive predictive marker for IVF outcome. To better understand consequences of antral follicle size as a marker for reproductive outcome, we aimed to obtain insight in follicle size-related granulosa cell processes, as granulosa cells play an essential role in follicular development via the production of growth factors, steroids and metabolic intermediates. Using the pig as a model, we compared gene expression in granulosa cells of smaller and larger follicles in the healthy antral follicle pool of sows, which had a high variation versus low variation in follicle size. Selected gene expression was confirmed at the protein level. Granulosa cells of smaller antral follicles showed increased cell proliferation, which was accompanied by a metabolic shift towards aerobic glycolysis (i.e. the Warburg effect), similar to other highly proliferating cells. High granulosa cell proliferation rates in smaller follicles might be regulated via increased granulosa cell expression of the androgen receptor and the epidermal growth factor receptor, which are activated in response to locally produced mitogens. While granulosa cells of smaller follicles in the pool are more proliferative, granulosa cells of larger follicles express more maturation markers such as insulin-like growth factor-1 (IGF1) and angiopoietin 1 (ANGPT1) and are therefore more differentiated. As both higher IGF1 and ANGPT1 have been associated with better IVF outcomes, the results of our study imply that including smaller follicles for oocyte aspiration might have negative consequences for IVF outcome.