ULTRASTRUCTURAL AND CYTOCHEMICAL CHARACTERISTICS OF PHAGOCYTES IN KURUMA PRAWN

Five types of phagocytes were observed in kuruma prawn Penaeus japonic us. Two of them were fixed phagocytes and three were hemocytes. Fixed phagocytes were detected in the heart and lymphoid organ. Phagocytes i n the heart were observed on basal lamina covering sarcolemma of heart muscles and the cells had many lysosomal granules (0.1 mu m in diamet er). Phagocytes in the lymphoid organ was characterized by numerous in terdigitating cell processes and few cytoplasmic granules. The hemocyt es were classified into three types, hyaline cell (HC), small granular cell (SGC) and large granular cell (LGC), according to the presence o f cytoplasmic deposit and size of granules. The HC had cytoplasmic dep osits and a few small granules (0.2 mu m in diameter). The SGC had sma ll granules (0.2 mu m in diameter) but the LGC contained large granule s (1 mu m in diameter). Lysosomal enzymes, such as acid phosphatase, b eta-glucuronidase and alpha-naphthyl butylate esterase, were detected in all five phagocytic cell types. Esterase activity was higher in the LGC than in any other phagocytes. Peroxidase activity was also detect ed in all phagocytes, although it was weak. Prophenoloxidase activity was found only in the SGC and LGC. These results indicate that the fix ed phagocytes are different from the hemocytes both in their ultrastru ctural and cytochemical characteristics.