Academic literature on the topic 'Skin – Histology'

There are 5 distinct aspects to this study. (i) Two histological stains for collagen were compared against each other for the first time, namely Herovici's technique and picrosirius-polarization. (ii) Skin samples from embalmed cadaveric tissue from human cadavers were compared against samples taken from surgical patients. (iii) Skin samples were studied from different regions of the body to assess if dermal structure correlates with scarring potential. (iv) Skin samples were sectioned in a plane parallel to the epidermis to gain further insight into dermal structure. (v) A novel basement membrane stain was produced. Type I and type III collagen are important structural constituents of dermis and play a crucial role in wound healing. Only two traditional histological methods are thought to differentiate between them, so avoiding the need for antibodies. These were compared against each other for the first time in order to establish differences in image quality and discrimination between Type I and type III collagen. Neither technique requires antibodies, however picrosirius requires polarisation microscopy. to result in a clearer, consistently reproducible collagen staining pattern than the picrosirius method and more importantly did not require elaborate apparatus to analyze. Additionally other cellular elements were visible. Skin samples for research are often obtained from surgical excision. This clearly limits which tissues are available for comparative study to those areas operated on. Studying samples from embalmed medical school cadavers has the great advantage of studying areas of the body not routinely available from common surgical procedures. It was therefore desirable to assess whether embalmed cadaveric tissues exhibited different properties by virtue of their age and the embalming process compared to fresh surgical specimens, in order to give confidence that studies utilising the former would be equally valid. To test this, 58 skin samples from embalmed medical school cadavers were compared to skin samples from 38 fresh operative specimens. The levels of tissue preservation and processing artefacts were similar in both groups. Embalmed medical school cadavers clearly offer an opportunity to study tissue areas not routinely available during surgery. This is the first time such a comparison has been made. Many things will affect the final appearance of the scar, but the single most important determinant is the body region affected. The most common areas for unfavourable scarring, specifically keloid or hypertrophic scarring have been shown to be the ear, deltoid and sternal areas. To test the hypothesis that there is no difference in histological structure of skin that correlates to body region, comparative histology was undertaken exploring the regional variations of skin characteristics in 58 cadaveric samples. Closely comparable samples were taken from the deltoid (9), abdomen (13), sternum (10), post-auricular (5), earlobe (12) and eyelid (9). Epidermal thickness, epidermal appendage density and collagen fibre orientation were examined and qualitative structural differences were assessed for each region Skin samples were then grouped by both topographical location of the body and scarring potential. Skin samples exhibited qualitative and quantifiable regional variations in the characteristics studied. Epidermal thickness and appendage counts did not correlate with scarring potential. Both however were statistically significantly higher in skin sampled from the head compared to the trunk. Bundles of collagen fibres in the reticular dermis were grouped according to their orientation in relation to the coronal plane; either parallel, oblique or perpendicular. The ratio of oblique to parallel fibres was statistically significantly higher in body areas with poorer scarring prognosis. This corresponds to a more disorganised arrangement of collagen fibres in these areas. Further qualitative understanding of dermal collagen fibres came from perpendicular to conventional histological samples. This new method stained basement membranes purple, cytoplasm was stained greenish-brown and nuclei dark brown. Collagen fibres were either thin and blue or thick and green. This method was compared to PAS staining and although required more preparative steps allows greater identification of other cellular structures.

Made available in DSpace on 2014-06-11T19:27:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-12-10Bitstream added on 2014-06-13T19:57:01Z : No. of bitstreams: 1 faria_naa_me_jabo.pdf: 988884 bytes, checksum: e245203de1795a549f7fa9d970a31585 (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Com o objetivo de fornecer subsídios para futuras pesquisas sobre aclimatação de equinos criados em clima tropical, um estudo sobre os aspectos histológicos e morfométricos da pele e anexos cutâneos de equinos de duas raças distintas foi realizado. Foram retiradas amostras do tegumento de 20 equinos (10 Árabes e 10 Quartos de Milha), em três regiões corporais distintas (cervical, flanco e glútea). As amostras foram submetidas ao processamento histológico de rotina. Utilizando um sistema de análise de imagens, foram quantificados e ou mensurados ductos sudoríparos, glândulas sebáceas, folículos pilosos e epiderme. Quanto aos aspectos morfométricos, foram encontradas diferenças (p≤0,05) nos parâmetros raça e região corporal. O tegumento de equinos Árabe e Quarto de Milha apresentou constituição histológica semelhante, nas três regiões analisadas<br>Aiming to provide subsidies for future research on acclimation of horses raised in tropical climate, we studied out this work on the histological and morphometric aspects of the skin and skin appendages of two distinct horses races. Skin samples were taken from 20 horses (10 Arabian and 10 Quarter Horses), in three different body regions (neck, flank and gluteus). Samples were analysed using a routine histological process. Through a system of image analysis, we quantified and measured or sweat ducts, sebaceous glands, hair follicles and epidermis. Morphometric differences were found (p ≤ 0.05) in race and body region parameters. Arab horses and Quarter Horses skin presented similar histological composition in the three analyzed regions

This project examined the role of the cytoskeleton in regulatory mechanisms of the amiloride-sensitive Na⁺ channels in isolated frog skin epithelium. The epithelium from ventral frog skin is a model tissue which has proved significant in our understanding of the basic principles involved in water and Na⁺ homeostasis. In particular, this project examines ways in which local (non-hormonal) and hormonal regulatory mechanisms adjust the Na⁺ permeability of apical membranes of frog skin epithelium. Both mechanisms contain factors that are known to increase the apical membrane Na⁺ permeability mainly by increases in the number of open channels. The origin of these new open channels is unknown but, it is postulated that they could arise either by activation of quiescent channels already present in the apical membrane, or by recruitment of channels from cytoplasmic stores. Regarding the latter hypothesis, we also examined the idea that the cytoskeleton might somehow be involved in the insertion of Na⁺ channels within vesicles, into the apical membrane. This is based on the fact that the cytoskeleton is involved in a similar mechanism whereby, in the toad urinary bladder, anti-diuretic hormone (ADH) causes the insertion of aggregates with water channels. Much current interest focuses on the role of the cytoskeleton in the regulation of epithelial Na⁺ channels. To test this hypothesis, we used noise analysis to examine the effects of disrupting the cytoskeleton, on two different mechanisms which bring about changes in open channel densities. The mechanisms are: (1) lowering mucosal Na⁺ concentration (non-hormonal), and (2) addition of arginine-vasopressin (A VP) (hormonal). Non-hormonal, autoregulatory changes in apical membrane Na⁺ conductance were examined by investigating the effects of reducing the mucosal Na⁺ concentration. Our results showed that lowering the mucosal Na⁺ concentration induced large increases in the open channel density in order to stabilise the transport rate. In addition, we observed an average 55-60% increase in the open channel probability, which implies that in epithelium from Rana fuscigula, changes of channel open probability are also an important mechanism in the autoregulation of channel densities in response to a reduction in mucosal Na⁺. The hormonal control of Na⁺ channels by A VP has been intensively studied by noise analysis and the patch clamp. Our results confirmed previous reports that A VP increases the Na⁺ transport rate by increasing the number of open Na⁺ channels, primarily through large changes in the total number of channels, without a significant change in open probability. Regarding the role of the cytoskeleton in regulation of Na⁺ channels and/or its possible role in control of inserting putative vesicles with Na⁺ channels, we studied the effects of disrupting the cytoskeleton on the two regulatory mechanisms. Disrupting microtubules with colchicine had no, or very little effect on either of the regulatory mechanisms. On the other hand, the integrity of the microfilaments was very important for the autoregulatory changes in the number of open channels. After cytochalasin B treatment, lowering the mucosal Na⁺ concentration did not result in the usual compensatory changes in channel densities. There was no prior evidence that cytochalasin B had any actual effect on the F-actin network in the frog skin epithelium. Accordingly, modified cytochemical techniques were designed to demonstrate and localise F-actin in the epithelial granular cells. The direct immunofluorescent method proved useful, but did not allow sufficient resolution to examine the changes to different populations of actin in the cells. We then modified an immunogold method to suit our conditions, and the results demonstrated the localisation of different pools of F-actin and showed the effects of the cytochalasin B and vasopressin.

Thesis (MSc)--University of Stellenbosch, 2002.<br>ENGLISH ABSTRACT: Specialized skin scales (generation glands) and undifferentiated skin scales were compared in three species of cordylid lizard, viz. Cordy/us cordy/us, Pseudocordy/us micro/epidotus and P. capensis. These skin derivatives were histologically examined and compared, using data existing in literature (Maderson, 1966; 1967; 1968a) with similar structures in gekkonids. Histological descriptions of cordylid skin structure were the same as those shown for gekkonids. Three types of generation glands were identified in cordylids (Van Wyk & Mouton, 1992), and these proved to be different to those existing in gekkonid species. These three types of generation glands were further compared regarding their ecdysis histology, which proved to be identical, thus, these glands differ only on gross morphological structure. Skin of all three species was also compared with regard to ecdysis, and while the histology of all three was identical, shedding activity was shown to differ in all three species. P. micro/epidotus displayed dormancy in the germinative layer for much longer periods of the year than either of the other two species, while P. capensis displayed very little dormancy. C. cordy/us displayed an intermediate pattern of ecdysis activity and dormancy. Autoradiography was performed on all species in both ecdysis activity and dormancy periods, to compare mitotic activity patterns in these periods. Generation gland activity appeared to correlate well with known testosterone peaks in the testicular cycle in all three species. Asynchrony between generation glands and skin scales was shown in all three species.<br>AFRIKAANSE OPSOMMING: GENERASIEKLIERE EN VERVELLINGSIKLUSSE IN GORDELAKKEDISSE (SAURIA: CORDYLIDAE) Drie spesies gordelakkedisse, Gordy/us cordy/us, Pseudocordy/us micro/epidofus en P. capensis, se gespesialiseerde velskubbe (generasiekliere) en gewone velskubbe word vergelyk. Hierdie velskubbe word deur histologiese metodes geëksamineer en vergelyk, met gebruik van data wat reeds in die literatuur bestaan (Maderson, 1966; 1967; 1968a), met soortgelyke strukture in Gekkonidae. Histologiese beskrywing van Cordylidae veistruktuur was identies met dié van Gekkonidae. Drie tipes generasiekliere was geïdentifiseer in gordelakkedisse (van Wyk & Mouton, 1992), en hulle verskil gedeeltlik van naverwante strukture in Gekkonidae. Hierdie drie tipes generasiekliere was verder vergelyk met betrekking tot hulle vervellingsiklus histologie, wat identies was. Dus verskil hulle net met betrekking tot hulle vorm. Vel is ook vergelyk met dieselfde metodes. Alhoewel daar geen verskille was met betrekking tot hulle histology nie, was die tye van aktiwiteit van kiem-sellae beduidend verskillend in alle spesies. In P. micro/epidofus het die kiem-sellaag russtadium baie langer geduur as in die ander twee spesies, terwyl P. cepensis amper geen russtadium getoon het nie. G. cordy/us het 'n intermediêre gedragspatroon vertoon tussen aktiewe en rustende fase met betrekking tot sy vervellingsiklus. Outoradiografie is gebruik op elke spesie, in beide aktiewe en rustende vervellingsfases, om verskille in mitotiese aktiwiteit te wys. Generasieklier aktiwiteit blyk te korreleer met pieke van testosteroonvlakke van die testikulêre siklus in al drie spesies. Asinkronie is aangetoon tussen generasiekliere en velskubbe in al drie spesies.

Orientador: Marcos Lania de Araujo<br>Banca: Marcia Rita Fernandes Machado<br>Banca: Joffre Guazzelli Filho<br>Resumo: Com o objetivo de fornecer subsídios para futuras pesquisas sobre aclimatação de equinos criados em clima tropical, um estudo sobre os aspectos histológicos e morfométricos da pele e anexos cutâneos de equinos de duas raças distintas foi realizado. Foram retiradas amostras do tegumento de 20 equinos (10 Árabes e 10 Quartos de Milha), em três regiões corporais distintas (cervical, flanco e glútea). As amostras foram submetidas ao processamento histológico de rotina. Utilizando um sistema de análise de imagens, foram quantificados e ou mensurados ductos sudoríparos, glândulas sebáceas, folículos pilosos e epiderme. Quanto aos aspectos morfométricos, foram encontradas diferenças (p≤0,05) nos parâmetros raça e região corporal. O tegumento de equinos Árabe e Quarto de Milha apresentou constituição histológica semelhante, nas três regiões analisadas<br>Abstract: Aiming to provide subsidies for future research on acclimation of horses raised in tropical climate, we studied out this work on the histological and morphometric aspects of the skin and skin appendages of two distinct horses races. Skin samples were taken from 20 horses (10 Arabian and 10 Quarter Horses), in three different body regions (neck, flank and gluteus). Samples were analysed using a routine histological process. Through a system of image analysis, we quantified and measured or sweat ducts, sebaceous glands, hair follicles and epidermis. Morphometric differences were found (p ≤ 0.05) in race and body region parameters. Arab horses and Quarter Horses skin presented similar histological composition in the three analyzed regions<br>Mestre

The skin is the largest organ of the body and provides many functions. Among tetrapod vertebrates, amphibian skin is semi-permeable and responsible for a greater proportion of water absorption and gas exchange. Myriad factors affect the physiological performance of amphibian skin. Morphological traits linked with amphibian skin physiology or ecology have remained difficult to discern because of a lack of quantitative comparative research and the discovery of sources of intraspecific variation that are mostly ignored in study designs. This thesis aims to address the effects of these sources of variation using a trait that is known to vary between sexes, among seasons, and among body regions and thought to be linked with physiology or ecology, skin thickness. The first source of variation addressed is sexual dimorphism. Specimens of the white-lipped treefrog, Litoria infrafrenata, that display sexual dimorphism in body size and skin thickness were used to test if body size was the main determinate of sexually dimorphic skin thickness. Size corrected values did not significantly differ between males and females, although the sample size was small. Seasonal variation in skin thickness has also been documented in some species, so the American bullfrog (Lithobates catesbeianus), the Northern leopard frog (L. pipiens), and the spring peeper (Pseudacris crucifer) from multiple months of the year were sampled to determine if skin thickness increased in the autumn or winter months. Seasonal skin thickening was only detected in L. catesbeianus, and skin from autumn and winter was significantly thicker than from earlier in the year. This pattern was also detectable in museum specimens collected 80 years ago, although the signal was damped, possibly due to preservation. Using a dataset of 10 species and published data, a general pattern was uncovered whereby the dorsal skin is the thickest region and the ventral thigh region is the thinnest. However, this pattern is not always true for every individual of every species (L. pipiens and P. crucifer) and in some species the dorsal skin is thinnest (Bokermannohyla alvarengai and Litoria infrafrenata). The same dataset found that skin thickness is significantly related to body size, as was found in the chapter on Litoria infrafrenata. Summer specimens of Lithobates catesbeianus were outliers below the interspecific regression line and winter specimens fell within the range of variation of other species, hinting that seasonal skin thickening could be renamed seasonal skin thinning in this species. Finally, a link between ecology and skin thickness was tested using the 10 species from previous analyses and data from the literature. At a phylogenetially broad scale, body size explained a greater amount of the variation in environmental parameters than skin thickness. At smaller taxonomic scales, skin thickness appears more closely linked with ecology. It is concluded that amphibians generally follow an allometric trend for skin thickness and when faced with suboptimal conditions over long periods of time, evolve integumentary structures like iridiophores to compensate for any physiological disadvantage of an ‘ideal’ skin thickness. In the interim, however, skin thickness may change, thus sacrificing e.g. mechanical support.

Made available in DSpace on 2014-10-09T12:35:35Z (GMT). No. of bitstreams: 0<br>Made available in DSpace on 2014-10-09T14:04:00Z (GMT). No. of bitstreams: 0<br>Tese (Doutoramento)<br>IPEN/T<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP