Phorate induced histopathological changes in the muscle of the common carpCyprinus carpio (Linnaeus, 1758)
The present study is aimed to investigate the effect of sublethal concentrations of phorate on the histology of muscle in the common carp, Cyprinus carpio (C. carpio). Fish were exposed to chronic sublethal toxicity (one-tenth of the LC50/96 hours - 0.071 ppm/l) of phorate (CSTP) for 1, 7, 15 and 30 days and the toxicity tests were carried out under laboratory conditions. On exposure for a period of 1 day to CSTP, mild degenerative changes were observed in the structure of the muscle of the fish. On further exposure for a period of 7 days, isolation and thinning of muscle fibers was observed. The muscle fibers exhibited longitudinal splitting with pyknotic nuclei. Cellular degeneration and increasing cytoplasmic vacuolization were also noticed. On exposure for a period of 15 days to CSTP, further splitting and thinning of muscle fibers was observed. Degeneration of muscle fibers, nuclei and cellular necrosis were also noticed. On exposure for a period of 30 days, further degeneration in the structure of the muscle was observed. There was heavy fibrilization with the loss of total muscular integrity and appearance of muscle fibers. The nuclei become highly pyknotic and scattered without any proper organization. The structure of the muscle was lost with cellular degeneration and cytoplasmic vacuolization in the fish C. carpio. The findings of the present investigation suggest that the frequency of pathological changes increase with the increasing exposure time to CSTP.