Morphology and histochemistry of the caudal gland of Corynopoma riisei Gill

Abstract

Males of the South American freshwater fish, Corynopoma riisei, have glandular masses on the caudal peduncle and fin which are partly enclosed by a scale‐covered pouch. Histo‐chemical examination reveals an extensive layer of large secretory cells superficial to the dermis appearing similar in form to typical mucous cells. PAS and Alcian blue staining indicate all cells produce muco‐ and/or glycoproteins and that a few cells are also synthesizing mucopolysaccharides. This secretion probably acts as a pheromone during courtship to stimulate or release female sexual response.