FINE STRUCTURE OF SCHIZONTS AND MEROZOITES OF EIMERIA NIESCHULZI

SYNOPSIS. Schizonts of E. nieschulzi lie in a vacuole within the host cell. After nuclear division the cell membrane invaginates forming merozoites. Differentiation of the pellicle and other organelles occurs while merozoites are still attached to the schizont cytoplasm. Merozoites have a pellicle thickened at the anterior end to form a polar ring. Radiating posteriorly from the ring, directly beneath the pellicle, are about 25 microtubules. Within the polar ring is a dense conoid. Extending posteriorly from within the conoid is a paired organelle. The paired organelle varies in size and shape in each generation of merozoites. Numerous toxonemes occupy the anterior half of the merozoites. Two paranuclear bodies are present in 1st generation merozoites. One or 2 granular bodies were seen in the anterior end of 2nd generation merozoites. In 3rd generation merozoites 6 or more granular bodies were seen anterior to the nucleus. Each merozoite has a single nucleus containing diffuse chromatin material. Elongate mitochondria and glycogen granules are present. The vacuole surrounding mature merozoites contains residual cytoplasm of the schizont and some granular material. Microvilli project into the vacuole from the host cell membrane. Copyright © 1968, Wiley Blackwell. All rights reserved