Electron microscopic studies of

Endogenous stages of Caryospora colubris Matuscha 1984 in the intestine of Coluber jugularis from Israel were studied by transmission electron microscopy. It is the first ultrastructural description of endogenous stages of Caryospora. The following stages are described : trophozoites, meronts microgamonts, macrogamonts and wall forming oocysts. The fine structure of the endogenous stages generally conforms with that of higher vertebrate Eimeria and Isospora. In the merozoites, however, the pellicle only lines the anterior tip, while the whole is bound by a single membrane with only fragments of an inner membrane. The wall formed around the oocyst, presumably the outer wall, is thick and contains a granular matrix. This stage of wall formation has been, thus far, not seen in other studied reptilian coccidia. Wall formation coincided with the disaggregation of type 1 wall forming bodies, while type 2 wall forming bodies remain unchanged