Histochemical studies of oxidoreductases, acid carbohydrates and glycoproteins in the epidermis of the electric eel Electrophorus electricus.

The activities of various oxidative enzymes and the presence of acid carbohydrates and acid glycoproteins in the epithelial cells and the mucous goblet cells of the epidermis of the Teleost Electrophorus electricus have been determined by means of a series of selected histochemical techniques of light microscopy. The enzyme activities show a distribution pattern confined mainly to basal cell layers and outer cell layers with a comparatively lower gradient in the transitional cell layers. A mixture of sialic acids of both N-acylated and O-acylated types is found in the mucous goblet cells and the functional significance of mucous production is related to the first line of defense against pathogenic colonization. The higher incidence of various oxidoreductases distributed throughout the entire epidermis is correlated with their key role which can play in the processes of cell differentiation and cell multiplication except for those regarding keratin formation which is not produced in the epidermis of most fish.