GILL TISSUE PATHOGENICITY AND HEMOCYTE BEHAVIOR IN THE CRAB PARATELPHUSA-HYDRODROMOUS EXPOSED TO LEAD CHLORIDE

Different size groups of Paratelphusa hydrodromous were exposed to sub lethal concentrations of 0.2-1.0 mg/L lead chloride solution for 60 da ys to study the hemogram responses in relation to gill pathogenic chan ges. The induction of hemocytopenia was a dose-dependent and time-rela ted phenomenon. Adult male crabs showed some tolerance to inorganic le ad. In granulocytes, long-term stress provoked intense granulation of the cytoplasm and hypertrophy of the nucleus. The presence of hemocyte infiltrate in gills was a characteristic sign of early inflammatory l esion. Random migration, encapsulation and hemocytosis were seen near the necrosed foci of gills. There were histological evidences in suppo rt that intravascular hemolymph clotting was initiated by lysed hyalin e hemocytes. The release of filamentous material by the lysed hyaline hemocyte was recognized as an apparent attempt to seal off the hemorrh agic lesion. The granulocyte proliferation was usually indicative of c hronic toxicosis and the absence of blood clots was considered to be a stage before the occurrence of mortality. Adherence, agglutination an d lysis of hemocytes may have reduced the number of circulating free h emocytes in toxified crabs.