The rabbit coccidium Eimeria flavescens Marotel and Guilhon, 1941: an electron microscopic study of its life cycle.

The endogenous cycle of Eimeria flavescens was studied in specific pathogen-free rabbits by means of histology and transmission electron microscopy. In total, five asexual generations were observed and two types of meronts and merozoites were found in each generation. Type A gave rise to a smaller number of thick polynucleate merozoites in which daughter merozoites were formed by endomerogony, while in the type B meronts slender uninucleate merozoites arose from ectomerogony. The first generation meronts were found in the crypts and proximal part of the villi of the duodenum and jejunum, whereas the three following generations developed in the superficial epithelium of the large intestine (cecum, vermiform appendix and colon). The last merogony as well as gamogony took place in crypts of the large intestine.