effects of lead nitrate on histo-cytological alterations of corpuscles of stannius of stinging catfish, heteropneustes fossilis

background: the present study investigated the effects of lead nitrate on the histo-cytological changes in the corpuscles of stannius (cs) of heteropneustes fossilis. methods: catfish, heteropneustes fossilis were subjected to 657.6 mg/l and 164.4 mg/l of lead nitrate for 96 h and 28 days, respectively. blood from fish was collected on 24, 48, 72 and 96 h in short-term and after 7, 14, 21, and 28 days in long-term experiment. blood was collected for analysis of calcium levels and cs were fixed for histological studies. results: plasma calcium levels of the fish remain unaffected at 24 h. the levels decrease after 48 h which persists till 96 h. plasma calcium levels of the fish exposed to lead for 7 days exhibit a decrease which persists progressively till 28 days. after 96 h, af-positive cells of cs exhibit increased granulation. no change in the nuclear volume of these cells has been noticed. an increased nuclear volume has been recorded in the af-negative cells of cs of 96 h lead exposed fish. after 14 days, the nuclear volume of af-positive cells decreases. heavy accumulation of secretory granules and decrease in the nuclear volume of af-positive cells have been recorded after 21 days which pronounced after 28 days. moreover, few degenerating cells have also been encountered. af-negative cells of cs exhibit an increase in the nuclear volume after 21 and 28 days lead treatment. conclusion: present findings suggest that exposure of the lead to catfish heteropneustes fossilis caused cs inactivity .