Abstract
As a step to elucidate the defense mechanism of Corbicula japonica against an enteric pathogen, Vibrio parahaemolyticus, morphology and activity of lysosomal enzymes in hemocytes of the bivalve were examined. C. japonica hemocytes were composed of spreading cells and round cells at a rate of 94.3 and 5.7%, respectively. Morphological feature of C. japonica hemocytes was similar to that of hemocytes of a neritid gastropod, Clithon retropictus. Histochemical studies on lysosomal enzymes of the hemocytes showed that C. japonica hemocytes stained for non-specific esterase, acid phosphatase and β-glucuronidase accounted for 98.7, 35.7 and 55.9%, respectively. Non-specific esterase-positive hemocytes of C. japonica were similar in rate to those of two neritid gastropods, C. retropictus and Nerita albicilla. Acid phosphatase-positive hemocytes of C. japonica were lower in rate than those of N. albicilla and higher than those of C. retropictus. β-glucuronidase-positive hemocytes were higher in rate than those of these gastropods. Low activity of acid phosphatase seems to be characteristic in hemocytes of estuarine molluscs.