The skin is a barrier between the internal and external environment of an organism. Depending on the species, it participates in multiple functions. The skin is the organ that holds the body together, covers and protects it, and provides communication with its environment. It is also the body's primary line of defense, especially for anamniotes. All vertebrates have multilayered skin composed of three main layers: the epidermis, the dermis, and the hypodermis. The vital mission of the integument in aquatic vertebrates is mucus secretion. Cornification began in apmhibians, improved in reptilians, and endured in avian and mammalian epidermis. The feather, the most ostentatious and functional structure of avian skin, evolved in the Mesozoic period. After the extinction of the dinosaurs, birds continued to diversify, followed by the enlargement, expansion, and diversification of mammals, which brings us to the most complicated skin organization of mammals with differing glands, cells, physiological pathways, and the evolution of hair. Throughout these radical changes, some features were preserved among classes such as basic dermal structure, pigment cell types, basic coloration genetics, and similar sensory features, which enable us to track the evolutionary path. The structural and physiological properties of the skin in all classes of vertebrates are presented. The purpose of this review is to go all the way back to the agnathans and follow the path step by step up to mammals to provide a comparative large and updated survey about vertebrate skin in terms of morphology, physiology, genetics, ecology, and immunology.

This study was carried out to assess the localization of hyaluronic acid (HA) and the distribution of glycoproteins in the gastrointestinal system of adult Hyla orientalis. Histochemical analysis of the gastrointestinal system in H. orientalis showed that mucous content included glycogene and/or oxidable dioles [periodic acid/Schiff (PAS)+], neutral or acid-rich (PAS/AB pH 2.5+), sialic acid residues (KOH/PAS+) and acid sulphate [Aldehyde fuchsin (AF)+] glycoproteins. However the mucus content was not the same in stomach, small and large intestine. The mucus content of stomach included only glycogene and/or oxidable dioles and sialic acid residues. Besides these histochemical methods, the localization of HA was detected using biotinylated hyaluronic acid binding protein labeled with streptavidin-fluorescein isothiocyanate (FITC). In the extracellular matrix of the submucosa, the reaction for HA was evident. Since HA was located in submucosa beneath the epithelial layer of gastrointestinal system, it has a significant role in hydric balance, and essential to provide the gastrointestinal system integrity and functionality. According to biometric results, there were statistical differences between small and large intestine in terms of the amount of material stained positive with PAS/AB, PAS, KOH/PAS and AF/AB. Additionally, number of goblet cells in the small and large intestine was significantly different.

We examined the effects of carbaryl in the digestive system of Ophisops elegans. Lizards were exposed once to different concentrations of carbaryl (2.5, 25 and 250 μg/g). After 96 h, findings related to the esophagus in all treatment groups were not conspicuous. The most important histological defects were observed in the stomach. In the small intestine, collapse of villi was prominent at high-dose. In the large intestine, disintegration in epithelial cells and scattered secretory granules of goblet cells were observed at high dose.

Carbaryl caused histopathological defects on the testes of O. elegans, so it is clear that carbaryl affects male fertility in O. elegans.

In the present study, the parotoid region, dorsal and ventral integuments of Lyciasalamandra billae and Lyciasalamandra luschani basoglui were investigated in terms of localization of hyaluronic acid (HA) and histochemical characteristics. HA immunoreactivity was carried out using biotinylated hyaluronic acid binding protein (B-HABP) labelled with streptavidin-fluorescein isothiocyanate (FITC). HA was mainly localized in the stratum spongiosum of L. billae and L. luschani basoglui for water homeostasis and skin functionality. Light microscopic observations revealed that the dorsal and ventral integuments of L. billae and L. luschani basoglui exhibited basic morphological characteristics of other amphibians: the epidermis was composed of a stratified squamous epithelium and the dermis subdivided into stratum spongiosum and stratum compactum. Two different types of dermal glands (mucous and granular glands) were identified in the spongious dermis of the dorsal and ventral integuments whereas in the parotoid region, three different types of glands (mucous, granular and parotoid glands) were examined.