ABSTRACT
Sporozoites of members of the genus Eimeria enter their respective hosts by penetrating epithelial cells of the intestinal mucosa. Species of Eimeria usually undergo several generations of schizogony and was believed to be for the most part genetically predetermined for each species. However, there is evidence to suggest that the number of cycles of asexual multiplication is not fixed. Some of the precocious strains of Eimeria undergo gametogony after a single generation of schizogony, indicating the possibility that sexual differentiation occurs after the merozoites have entered cells to begin gametogony perhaps as a result of some sort of cytoplasmic stimulus exerted by the host cell. The isolation of precocious strains of Eimeria species and the changes in schizogony brought about by serial passages of E. tenella through chick embryos point to the fluidity of the genome of this group of parasites as well.
