A study on the structure of the whiting integument (Merlangius merlangusL.)

Abstract
The histology and histochemistry of whiting skin was studied in larval, juvenile and adult fish. The adult specimens were obtained throughout the year but there was no evidence of seasonal variation in the areas of the body sampled. The skin of the whiting is considerably more complex than that of any other teleost fish which has been described in detail. The epidermis of the mature fish comprises five layers, consisting of Malpighian cells and a variety of other structures including large cystic bullae, which ultrastructurally and histochemically are relatively amorphous but comprise a major proportion of the epidermis. A reticulum of epidermal melanocytes occurs above these structures and two types of mucous cell are described. The major histochemical feature of the epidermis was the alkaline phosphatase reaction, similar to that found in higher animals. Succinic dehydrogenase activity was found at all levels. The epithelial mucins were mainly acid mucopolysaccharide with a small sialic acid component and a greater proportion of sulphated muco-substance. The dermis was morphologically similar to that of other scaled fishes. Mast cells were particularly prominent and occasional non-pigmented ‘melanophores’ were seen.