Abstract:
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Objective】This study aimed to systematically characterize the histological structure, cellular ultrastructural features, and distribution patterns of mucous cells and club cells in dorsal, abdominal, and tail skin of
Euchiloglanis kishinouyei, thereby providing histological evidence for elucidating its habitat adaptation mechanisms and supporting germplasm resource conservation.【
Method】Three healthy adult female fish were selected, and their skin tissues were collected from the dorsal, abdominal, and tail regions. The samples were examined by light microscope and transmission electron microscope after hematoxylin-eosin staining (HE) and Alcian blue-periodic acid Schiff staining (AB-PAS). ImageJ was used to conduct quantitative analysis on the thickness of epidermal and dermal layers, as well as the numbers of mucous cells and club cells in the dorsal, abdominal, and tail skin.【
Result】The skin of
Euchiloglanis kishinouyei was scaleless and consisted of the epidermis, dermis, and subcutaneous layer. Pigment cells were present in the dermis of dorsal and tail skin, whereas adipose tissue was abundant in the subcutaneous layer of abdominal skin. Transmission electron microscope observation results revealed that the epithelial cells in the epidermis, with numerous fingerprint-like micro-ridges on the free end of these cells; abundant desmosomal junctions were observed between epithelial cells; fibroblasts were present in the middle dermis, adjacent to densely arranged bundles of collagen fibers. Epidermis thickness was in the order of abdomen > dorsum > tail, and the dermis thickness of dorsal and abdominal skin was significantly greater than that of the caudal skin (
P<0.05, the same below), with only a slight difference in thickness between the dorsal and abdominal dermis, while the caudal dermis was the thinnest. Mucous cells were mainly distributed in the superficial epidermis and were dominated by type III mucous cells, with a small number of type II and type IV mucous cells also observed. The number of mucous cells in the dorsal skin was significantly higher than that in the abdominal and tail skin. No significant difference was observed in the number of club cells among the skin at different parts of
Euchiloglanis kishinouyei (
P>0.05).【
Conclusion】The scaleless skin of
Euchiloglanis kishinouyei contributes to the establishment of a physical barrier and chemical defense system adapted to torrent gravel habitat through coordinated features including epidermal thickening, predominance of type III mucous cells, and relatively uniform distribution of club cells. Differences in skin structure and cellular distribution in different parts of
Euchiloglanis kishinouyei reflect functional responses to differential external stresses, such as hydraulic impact and substrate abrasion.