ULTRASTRUCTURAL STUDY OF EARLY STAGES OF ASEXUAL MULTIPLICATION AND MICROGAMETOGONY OF TOXOPLASMA GONDII IN THE SMALL INTESTINE OF THE CAT

Toxoplasma gondii undergoes schizogony and microgametogony in the epithelial cells of the cat ileum. On the basis of cytoplasmic structures, it is impossible to distinguish between the early stages of these processes but nuclear differentiation appears to have occurred. In the early schizont the chromatin is distributed in small patches throughout the nucleus but in the nucleus of the microgametocyte the chromatin is condensed into a few large areas. In the schizont, the first distinguishing cytoplasmic features are the appearance of the dome-shaped membranes of the merozoite anlagen. In the schizogonic process, nuclear division precedes merozoite formation which occurs by multiple internal budding in a manner similar to endodyogeny. The appearance of flagella is the first cytoplasmic feature to distinguish the microgametocyte. Microgamete formation is similar to that reported for other coccidian species. The microgamete consists of a dense elongate nucleus anterior to which is a single mitochondrion. The anterior consists of a perforatorium and two flagella between which 4 microtubules run longitudinally.