[Changes in the cellular ultrastructure of the gill epithelium in Tilapia under the action of cadmium on the fish].

The ultrastructure of the Tilapia gill epithelium cells was studied under condition of a prolonged (2 months) treatment of these fishes with cadmium in a concentration of 5 mg/l. A decrease in the quantity of chloride cells in the primary gill epithelium, and of respiratory cells in the secondary epithelium was found. The chloride and mucous cells are, respectively, most sensitive and most resistant to the influence of cadmium. The accumulation of lysosomal structures in chloride and respiratory cells was observed, in addition to a reduced surface relief in these and some damage in mitochondria of the former being noticed. A slow development of reparation processes in the tilapia gill epithelium cells was followed after the cancellation of cadmium effect. No restoration of the original ultrastructural pattern of the gill epithelium cells was observed after a 1.5-month inhabitance of Tilapia in clean water.