(Redrawn after Levine 1961)
The oocyst leaves the host in an undeveloped state, but within a few day undergoes a process of sporulation to produce sporozoites within. Eimeria always produces four sporocysts, each containing two sporozoites. Related genera may have different pattersn such as two sporocysts each with four sporozoites. The positions, and presence or absence, of refractile bodies and sporocyst or oocyst residual bodies are important features for identification of species.