MORPHOLOGICAL AND FUNCTIONAL CHARACTERIZATION OF THE HEMOCYTES OF THE SCALLOP, CHLAMYS FARRERI

Light, transmission and scanning electron microscopical studies were carried out to characterize the hemocytes of the scallop Chlamys farreri (Jones & Preston). Five types of hemocytes were recognized: type 1 small hyalinocytes (2.44 ± 0.11 μm, 45% to 50%), type 2 large hyalinocytes (4.83 ± 0.28 μm, 15–20%), type 3 small granulocytes (4.07 ± 0.15 μm, 15% to 20%), type 4 medium granulocytes (7.20 ± 0.26 μm, 20–25%) and type 5 large granulocytes (13.87 ± 0.73 μm, 3% to 5%). Granulocytes showed larger sizes and smaller N/C ratios than hyalinocytes. The mean hemocyte concentration was about (3.03 ± 0.11) × 107 cells mL−1. Among hemocytes, 42.6% are granular cells and 57.4% are agranular cells. These gave a relatively systematic classification scheme for hemocytes of Chlamys farreri. Three kinds of granules were identified: high electron-dense granules, low electron-dense granules and medium electron-dense granules based on TEM studies. Both granulocytes and hyalinocytes showed phagocytic response to the two strains of bacteria, E. coli and Rickettsia-like organisms. The phagocytic ability of granulocyte was significantly higher (30% to 40%) than that of hyalinocyte (4.8% to 14%).