[Intranuclear development of the macrogametes of the coccidian, Tyzzeria parvula].

The fine structure of macrogametes of a goose coccidium Tyzzeria parvula has been studied, intranuclear localization of these being discovered. Unlike other coccidia, macrogametes of T. parvula display only one type of wall-forming bodies. Deep invaginations are formed on the surface of macrogametes, in which fragments of host cell nucleoplasm, separated with the membrane of parasitophorous vacuole, are invaginating. They may be connected with process of parasite's feeding.