[The effect of cadmium on the gill structure in Tilapia]. / Vliianie kadmiia na strukturu zhabr tiliapii.

The effect of a long-term (2 months) exposure to cadmium (5 mg/l), with a subsequent recovery in clean water, upon gill structural organization of Mozambique tilapia was studied using scanning and light microscopy. Some of nonspecific components of the gill response on cadmium action were revealed: hypertrophy and fusion of respiratory lamellae, swelling and lifting of the epithelium from capillaries, vascular stasis. In addition, heavy metal-specific components of this reaction were found, which are involved in the development of epithelial necrosis and leucocyte infiltration into the tissue. The gill ultrastructure recovery was not achieved completely even after a 1.5 month exposure of fishes in clean water.

[Changes in the cellular ultrastructure of the gill epithelium in Tilapia under the action of cadmium on the fish]. / Izmenenie ul'trastruktury kletok zhabernogo épiteliia tiliapii pri deistvii na ryb kadmiia.

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.