ABSTRACT
Oocysts of Isospora chalchidis [Amoudi, 1989] were described from the feces of the skink Chalcides ocellatus in Egypt. Non- sporulated oocysts were spheroidal, measuring 20 [l8.5-21] mum in diameter and contained granulated zygotes. Sporulated oocysts had the same dimensions of the non-sporulated ones and each contained two sporocysts. Sporocysts were ovoid with stieda and sporocyst residual bodies. Sporulation time was 50 hours at room temperature. Merogony and gamogony occurred in the intestinal mucosa. Electron microscopic investigations showed that meronts, merozoites, gamonts and gametes developed in a narrow parasitophorous vacuole within the host- cell nucleus. Nuclei of meronts were surrounded by rough endoplasmic reticulum. Merozoites showed the main characteristics of motile stages of apicomplexa. Macrogametes contained a large nucleus, two types of wall-forming bodies and a large amount of lipid inclusions. Nuclei of microgamonts were peripherally arranged and lacked nucleoli. Microgametes were flagellated