Development in cell cultures of Eimeria vermiformis Ernst, Chobotar and Hammond, 1971

Development of Eimeria vermiformis from sporozoite to mature first-generation schizonts in cultured bovine kidney cells, Madin-Darby bovine kidney cells, and primary cultures of whole mouse embryos is described. Intracellular sporozoites were seen at 5 min, and for as long as 120 h after inoculation. Sporozoites were observed penetrating cells, with uninucleate trophozoites and immature schizonts with 2--6 nuclei first appearing 24 h after inoculation. Schizonts with 6 or more nuclei, as well as mature schizonts containing first-generation merozoites, were first seen between 36 and 48 h after inoculation of all 3 cell types used. The first indication of merozoite formation was determined by the appearance of small protuberances of cytoplasm at the periphery of schizonts. Merozoites began development at the periphery of schizonts and were later observed radiating from a central body of cytoplasm, 14--20 merozoites being formed. Some mature schizonts retained a small spherical residual body after merozoite formation was completed. After the rupture of schizonts, intracellular merozoites, which contained anterior and posterior refractile granules, were seen at 48, 72 and 96 h postinoculation. Merozoites were not seen entering or leaving cells. No further development was observed.