Comparative studies on the histological structure of skin in fresh and brackish water fish

Abstract

Objective: To characterize the skin structure in fresh and brackish water fish and make comparison between them.Design: Descriptive studyAnimals: Two types of brackish water fishes were used sea bass (Dicentrarchus labrax) and grey mullet (Mugil cephalus) & two types of fresh water fishes were used catfish (Clarias lazera) and common carp fish (Cyprinus carpio).Procedures: Twenty adult fish (sea bass, grey mullet catfish & common carp), five of each species were anaesthetized. Skin specimens were taken from the dorsum side and fixed in 10% neutral buffered formalin. The specimens were processed, treated with the normal histological technique, sectioned, stained with different stains and examined by the light microscope.Results: The skin of the four species was comprised of epidermis, dermis and hypodermis. The epidermis was consisted of three distinct layers. Two types of unicellular glands were present in the epidermis such as club cells in the epidermis of catfish and common carp and mucous cells in the epidermis of all fishes. The mucous cells gave positive reaction to AB/PAS stain. The club cells were positively reacted to Bromophenol Blue stain. The dermis was formed of the stratum spongiosum and the stratum compactum. The latter was stained more deeply than that of spongy layer. Hypodermis consisted of a layer of connective tissue containing adipocytes. Conclusion and clinical relevance: The present study concluded that the skin is adapted to the nature of the environment in which the fish live.