RESPONSES OF HEMOCYTES AND GILL TISSUES TO SUBLETHAL CADMIUM CHLORIDEPOISONING IN THE CRAB PARATELPHUSA-HYDRODROMOUS (HERBST)

The hemocytic and gill tissue responses of the crab Paratelphusa hydro dromous (Herbst) to a wide range of sublethal concentrations of cadmiu m chloride (0.02-0.50 muM/L) were examined after a 30-day exposure usi ng hemocyte counts (THC and DHC) and lamellar pathology. A continued r eduction in the hemocyte counts and selective changes in the numbers o f hyalinocytes and eosinophilic granulocytes was evident in the toxifi ed crabs. Under sublethal stress, the hyalinocytes developed eccentric nuclei, granular cytoplasm and membrane blebs. Atypical shape, lobate nucleus, dense cytoplasmic deposits and granuloplasmic vacuoles were frequently observed in the granulocytes. Greater proliferation of proh emocytes and abnormal hemocyte morphology indicated cadmium-induced ne oplastic transformation of hemocytopoietic organs. No major structural changes in the gills were noted at 0.02 muM CdCl2. Nodular gill disea se (NGD), hemocytic hyperplasia and sloughing of walled off hemocytes were prominant lesions after 0.50 muM cadmium chloride exposure.