An ultrastructural study of the asexual development of a presumed Isospora sp. in mononuclear, phagocytic cells of the evening grosbeak (Hesperiphona vespertina).

摘要: Merozoites of a presumed Isospora species were invested by close-fitting vacuole host- cell origin following their entry into mononuclear, phagocytic cells the evening grosbeak (Hesperiphona vespertina). Here, merozoites transformed trophozoites that bound plasmalemma, beneath which lay short segments inner membrane complex from pellicle former mero- zoite. Nuclear division followed and in schizonts various sizes (probably representing several asexual generations), merozoite buds appeared around peripheral cytoplasm. also seen form- ing within internal cytoplasm some schizonts. A conical, anterior projection nucleus containing microtubules (the centrocone) an adjacent pair centrioles often forming merozoites. Some maturing singly distended parasitophorous vacuoles cells, whereas other vacuoles, groups seen. In addition to well- documented "standard" apicomplexan features, sp. contained two spheroidal vesicles closely layers membrane, near Golgi complex. The possessed about 26 pellicular microtubules, three polar rings, or rhoptries, more micropores. Two types seen; one, electron-dense second, considerably less so. certain ultrastructural resemble bradyzoites many heteroxenous, isosporoid than conventional, gut-based Eimeria.