Corpuscles of Stannius of a teleost Heteropneustes fossilis following intoxication with a pyrethroid (cypermethrin)

Fresh water fish, Heteropneustes fossilis were subjected to 5.76 μg/L (0.8 of 96 h 50% lethal concentration, LC50) and 1.44 μg/L (0.2 of 96 h LC50) solution of cypermethrin for short-term (96 h) and long-term (28 days), respectively. After short-term cypermethrin exposure, the plasma calcium levels of Heteropneustes fossilis showed a decrease which persisted for 96 h. In long-term exposed fish, following 7 days exposure to cypermethrin there was a decrease in the plasma calcium level. This decrease persisted progressively up to 28 days. Up to 72 h following cypermethrin exposure there was no change in the AF-positive and AF-negative cells of CS. Increased granulation in the AFpositive cells of CS was recorded following 96 h exposure to cypermethrin. The nuclear volume of AF-positive cells remained unaffected. The AF-negative cells of CS had increased nuclear volume only at 96 h cypermethrin exposure. In cypermethrin-treated fish the CS remained unaffected up to 7 days. The nuclear volume of AF-positive cells decreased at 14 days. Increased granulation in the AF-positive cells was noticed following 21 days of exposure to cypermethrin. The nuclear volume of these cells further decreased. These changes were exaggerated and few degenerating cells were encountered after 28 days. No change was observed in the AF-negative cells of CS until 14 days of cypermethrin exposure. These cells exhibited an increase in their nuclear volume after 21 and 28 days treatment.