Experimental lead nitrate poisoning: microscopic and ultrastructural study of the gills of tench (Tinca tinca, L.).

A microscopic, ultrastructural, and morphometric study was made of the gills of tench (Tinca tinca, L.) subjected to acute experimental lead nitrate poisoning. Twenty-one adult tench were subjected to poisoning and a further 22 were used as controls. Lesions were characterized by the appearance of edema and epithelial hyperplasia and necrosis, both in cells forming part of the filtration barrier and in those in the interlamellar space. These processes developed in the course of the experiment, leading to the death of tench after 12 to 15 days of exposure to 75 ppm lead nitrate, at which point the concentrations of lead in the gills had reached their maximum.