GAMETOCYTOGENESIS OF LEUCOCYTOZOON-SMITHI

Development of young gametocytes of Leucocytozoon smithi into morpholo gically mature forms was studied using electron microscopy. Gametocyto genesis began on day seven post inoculation when merozoites, released from ruptured hepatic schizonts, developed into gametocytes within mon onuclear phagocytes or leukocytes (monocytes or lymphocytes). No gamet ocytes were observed in any erythrocytes or polymorphonuclear leukocyt es. Two gametocyte forms, round and elongate, were observed. Immature round gametocytes occurred on days 7-10 post inoculation in the deep v asculature of liver, lung and spleen. Mature elongate gametocytes were observed beginning on day 12 post inoculation in both the deep tissue vasculature and peripheral circulation of the turkey host. Growth and elongation of the gametocyte resulted in distortion of the host cell and its nucleus. The host cell nucleus initially was elongated and dis placed to one side or indented by the growing parasite. Eventually, th e nucleus was laterally compressed or split into two or three fragment s. The compressed host cell cytoplasm was displaced longitudinally and stretched over the parasite to form horn-like cytoplasmic extensions from each end. The potential role of microtubules in the elongation of the gametocyte and its host cell, and possibly in the indentation and splitting of the host cell nucleus, is discussed.