Observations on the ultrastructure of the late sporoblasts and the initiation of sporozoite formation in Eimeria brunetti.

The ultrastructure of the late sporoblast and the initiation of sporozite formation in E. brunetti was examined in oocysts which had been allowed to sporulate for 24 hours at 27 degrees C. The late sporoblast was ellipsoidal in shape and possessed two nuclei, and with associated Golgi bodies, situated at either end of the organism. Its cytoplasm contained numerous polysaccharide granules, electron translucentral region of the plaques. Sporozoite formation was similar to the initiation of merozoite formation in the schizont. Endodyogeny did not appear to be involved in the process of sporozoite formation.t vacuoles, dense bodies, mitochondria, and some strands of rough endoplasmic reticulum. The sporoblast, at this stage, was enclosed by two unit membranes. Sporozoite formation was initiated by the appearance of a dense plaque at either end of the organism in the vicinity of a nucleus, adjacent to the limiting membrane of the sporoblast. A conoid was present in the central region of the plaques Sporozoite formation was similar to the initiation of merozoite formation in the schizont. Endodyogeny did not appear to be involved in the process of sporozoite formation.