Mechanism of Gaseous Exophthalmia in the Atlantic Cod, Gadus morhua L.

Abstract

Gadus morhua L. in captivity of ten develop unilateral or bilateral exophthalmia, characterized by the accumulation of gas bubbles in the eye.Rete mirabile-like organization of capillaries in the choroid "gland" in association with the glandular pseudobranch, which is a rich source of carbonic anhydrase in fishes, are involved in gas secretion in the eye of cod. Intraperitoneal injections of Diamox and pseudobranchectomy prevented exopthalmia in the fish.Presence of glycogen and carbonic anhydrase in the choroid gland in relation to gas secretion in the eye suggests a parallel with the process of gas secretion in the teleostean swimbladder.Gas secretion in the eye of cod resulting in exopthalmia would seem to be a malfunctioning of the choroid gland-pseudobranch complex in the fish triggered by unknown stimuli.