The opercular gland of the cleaner‐wrasse Labroides dimidiatus (Labridae), a light‐, electron and scanning electron microscopic investigation

Abstract

A histological and ultrastructural examination of the opercular gland of the cleaner‐wrasse Labroides dimidiutus has demonstrated that the slimy envelope which covers the animal at night is mainly produced by large mucous goblet cells in a folded epithelium; there is a high number of acidophilic secretory cells. At the ultrastructural level, both cell‐types open at the surface of the epidermis. Preliminary experiments with pilocarpine, atropine and the α‐blocker propranolol reveal a neural regulation of mucus discharge. Also, the rich vascularization of the gland could indicate a hormonal control e.g. by prolactin. The secretory products of both types of goblet cells are discussed in relation to their possible antibiotic properties.