[Ultra-fine organization of the goose coccidium Eimeria kotlani. I. Intranuclear development of macrogametes].

The ultrastructure of the macrogamete stage of Eimeria kotlani has been studied. The peculiarity of this eimerian parasite is that its development procedes within the host cell nucleus. The ultrastructure of the macrogamete of E. kotlani has much in common with that of other eimerians that are localized in the host cell cytoplasm. The differences noticed concern, first of all, the structural organization of wall forming bodies of both types (WF-1, WF-2). The WF-1 are originally arranged around the WF-2, as small electron opaque granules making a dark ring, to move towards the periphery of the macrogamete body with maturation. The WF-2 of E. kotlani macrogametes lack a labyrinth structure so characteristic of WF-2 of macrogametes of other eimerian species. The macrogamete of E. kotlani is limited with three membranes, the innermost membrane is interrupted. Pinocytosis is presumably a mode of the parasite's nutrition. The nutrients are supposed to be transported by vesicles originating from the nucleoplasm of the host cell and limited with two membranes. In result, the remaining nucleoplasm looks as a narrow space of small islets. The host cell cytoplasm reveals some degenerative changes only by the final step of the parasite's development.