Eimeria media Kessel 1929: comparative study of endogenous development between precocious and parental strains.

Endogenous development of a pure strain of Eimeria media and of a precocious line derived from this strain was studied in specific pathogen-free (SPF) rabbits. Endogenous development of the parental strain comprised three generations and the gamogony began 76 h post-inoculation (pi). Two types of meronts were observed in each generation. The type A meronts gave rise to large, polynucleated merozoites present in low numbers. Multiplication was carried out by endomerogony. Within type B meronts, merozoites arose from ectomerogony. These were slender and more numerous than those of type A. The sporozoite refractile body was divided and distributed into the first and second generation merozoites but not into the third. The endogenous development of the precocious line was similar to that of the parental strain except that no refractile body was observed and the last merogony was absent. Gamogony appeared 60 h pi.