ABSTRACT
Most of the more fundamental aspects of the structure and ultrastructure of members of the families Eimeriidae and Sarcocystidae have been known for a number of years and presented in several excellent reviews. Sporulation at the ultrastructural level for Eimeria brunetti and Toxoplasma gondii has been reviewed. There have only been two other reports on the ultrastructure of sporulation of Eimeria oocysts; sporulation of E. maxima and sporulation of E. tenella. There have been a number of studies on the ultrastructure of excystation of coccidian oocysts, including T. gondii, Cryptosporidium muris and Cryptosporidium parvum. In addition to providing information on the fine structure of coccidian parasites, electron microscopy has been useful in examining the interactions that take place between the parasites and the host cells. There have been many studies using scanning electron microscopy principally to examine the effects of coccidian parasites on the host intestinal wall.
