title: Extraintestinal stages fo Isospora ohioensis from dogs in mice.
abstract: The development of Isospora ohioensis was studied in mice by feeding tissues of mice inoculated with oocysts to coccidia-free dogs and by the examination of mesenteric lymph nodes using light and electron microscopes. Extraintestinal organs of mice became infectious to dogs within 1 day after ingesting oocysts and remained infectious for at least 211 days after inoculation (DAI). Isospora ohioensis sporozoites were found in lymphoreticular cells of mesenteric lymph nodes of mice from 1-374 DAI. Intracellular sporozoites were located in parasitophorous vacuoles. Sporozoites grew from 5--6 to 11--16 micron in length on the 39th DAI but never lost the 2 crytalloid bodies typical for coccidian sporozoites. PAS-positive granules accumulated gradually in intracellular sporozoites with duration of infection in mice. The appearance of parasitophorous vacuoles varied with duration of infection. Beginning with 7 DAI, the vacuole contained a marginal zone of electron-dense material (up to 0.8 micron wide), giving the appearance of a cyst wall or sheath under the light microscope; a true cyst wall was was not found.
mesh_terms: D000818:Animals; D003048:Coccidiosis / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D004283:Dog Diseases / Q000469:parasitology* / Q000635:transmission; D004285:Dogs; D005260:Female; D007549:Isospora / Q000648:ultrastructure*; D051379:Mice / Q000469:parasitology; D012376:Rodent Diseases / Q000469:parasitology* / Q000635:transmission