Immunohistochemical localization of somatostatin, insulin and glucagon in the principal islets of the anglerfish (Lophius americanus) and the channel catfish (Ictalurus punctata)

Somatostatin, insulin and glucagon were localized in the principal islets of the anglerfish (Lophius americanus) and the channel catfish (Ictalurus punctata) by means of the unlabeled antibody‐peroxidase‐antiperoxidase immunocytochemical method. Both species showed a similar ratio of positive cells 9:6:4 (insulin:somatostatin:glucagon), but the interrelations of the three cell types differed between species. The large number of somatostatin‐positive cells may be indicative of an important role for this hormone in teleost physiology. The principal islets appear to be a good source of tissue for further work on somatostatin.