title: Complete development of Isopora suis of swine in chicken embryos.
abstract: Development of the swine coccidium , Isospora suis, in embryonated chicken eggs is described. The allantoic cavities of eight-to-ten-day-old white Leghorn embryos were inoculated with either 100,000 or 200,000 sporozoites. Developmental stages morphologically similar to those found in the intestines of piglets were present in the endodermal layer of the chorioallantoic membrane (CAM), beginning three days post inoculation (PI). No stages were found in the mesodermal or ectodermal layers of the CAM and none were observed in heart, lung, liver, or spleen. Type I meronts and merozoites were found on days 3 through 10 PI. Type II meronts and merozoites were found days 4 through 10 PI. Mature microgamonts , macrogamonts, and oocysts were found on days 7 through 10 PI. Oocysts appeared to be retained in the endodermal cells and in ovo sporulation did not occur. Attempts to sporulate CAM-derived oocysts were not successful. Isospora suis was not pathogenic for embryos under the conditions of this study. This study represents the first fully documented report of complete development of a mammalian coccidium in chicken embryos.
mesh_terms: D000482:Allantois / Q000469:parasitology*; D000818:Animals; D002642:Chick Embryo / Q000469:parasitology*; D004707:Endoderm / Q000469:parasitology; D005321:Extraembryonic Membranes / Q000469:parasitology*; D007422:Intestines / Q000469:parasitology; D007549:Isospora / Q000254:growth & development* / Q000472:pathogenicity / Q000502:physiology; D013170:Spores; D013552:Swine / Q000469:parasitology