[The effect of cadmium on the gill structure in Tilapia]

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.