The ultrastructure of macrogametes of Eimeria ferrisi Levine and Ivens 1965 in Mus musculus.

Macrogametes of Eimeria ferrisi occurred in epithelial cells of the cecum and colon of Mus musculus and were studied by electron microscopy. Young stages were identified as macrogamonts by the presence of wall-forming bodies. At first an outerlimiting membrane and remnants of the inner membrane complex of the former merozoite pellicle were present; the latter was later lost but in mature macrogametes 3 limiting membranes were observed. Type II wall-forming bodies appeared before type I; the former developed in expanded cisternae of the endoplasmic reticulum whereas the latter were smaller in size and appeared in the ground substance of the cytoplasm. After formation of the oocyst wall the bodies of the 2 types were no longer visible. The presenceodies of the 2 types were no longer visible. The persistence of micronemes in mature macrogametes and the presence of numerous layers of rough endoplasmic reticulum during wall formation have not been previously reported.