CARBOHYDRATES IN THE EPIDERMAL MUCOUS CELLS OF A FRESH-WATER FISH MASTACEMBELUS-PANCALUS (MASTACEMBELIDAE, PISCES) AS STUDIED BY ELECTRON-MICROSCOPIC CYTOCHEMICAL METHODS

Carbohydrates in the mucous cells of the epidermis of the fish Mastace mbelus pancalus were studied by means of electron-microscopic cytochem ical methods using physical development procedures. Three types of muc ous cells (types A-C) were differentiated on the basis of the reactivi ties of the secretory products elaborated by them. The carbohydrate co ntents of mucous globules predominantly comprised sulfate esters and t races of oxidizable vicinal diols in type-A cells, oxidizable vicinal diols in type-B cells, and moderate amounts of both sulfate esters and oxidizable vicinal diols in type-C cells. Glycogen particles were als o found to occur in the cytoplasm of these cells and glycoproteins con taining oxidizable vicinal diols were visualized in Golgi cisternae, r ough endoplasmic reticulum, nuclear envelopes, and plasma membranes. I n the type-A and type-B cells situated in the superficial layers of th e epidermis, extensive cisternae of the Golgi apparatus and copious ro ugh endoplasmic reticulum suggested the active syntheses of secretory contents, in contrast to the type-C mucous cells, which displayed poor development of these organelles, in the deeper layers.