Ultrastuctural study of the phagocytic activities of splenic macrophages in tilapia (Oreochromis niloticus)

The main stages of the phagocytic process after the intraperitoneal injection of colloidal carbon to tilapia (Oreochromis niloticus), was ultra-structurally documented. Carbon particles were initially in diffuse form in the cytoplasm but they gradually formed discrete electron dense bodies that later fused with cytoplasmic granules to form phagolysosomes. Ultra structural results demonstrate that colloidal carbon is actively phagocytized by cytoplasmic granules (lysosomes) in the spleen of O. niloticus. Direct phagocytic reaction of cells in the presence of an antigen is therefore very important in immunity.