Date of Award:

5-1-1973

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

Datus M. Hammond

Committee

Datus M. Hammond

Committee

Thomas L. Bahler

Committee

Hugh P. Stanley

Abstract

The sporozoites and 1st, 2nd, and 3rd generation schizonts of Eimeria magna were studied. The tissue in which these stages were found was fixed Karnovsky's fixative, and post fixed in 2.5% osmium tetroxide. Some of the tissue was prestained with uranyl acetate and phosphotungstic acid before examination with the electron microscope. Intracellular sporozoites observed in 24-hr ligated intestine had fewer amylopectin granules, and more mitochondria than those fixed immediately after inoculation. One or two Golgi apparatuses were seen in close association with the nucleus. The inner membrane complex of the pellicle was still intact, and no indication of nuclear division was seen. Food vacuole-like structures were observed in these sporozoites. Mature first-generation schizonts were observed in rabbit intestinal tissue fixed 3 days after inoculation. The uninucleate merozoites in these had rhoptries, micronemes, Golgi apparatuses, and refractile bodies. Such merozoites evidently penetrated new host cells before developing further. During transformation of these merozoites into trophozoites, the inner membrane of the pellicle disappeared in some areas while remaining intact in others. At this stage, the endoplasmic reticulum was prominent. Formation of second-generation meroznites was observed in specimens fixed 3½ days after inoculation. The merozoites developed at the surface of the schizont, and organelles were incorporated as the immature merozoite increased in length. In some schizonts, conoids without any other associated organelles, except for annuli and microneme-like structures in some cases, were seen in the residual body. Some merozoites were attached laterally to the residual body rather than terminally. In the area of attachment, the inner membrane complex was present, but not the outer membrane, which covered the remainder of the merozoite. Second-generation schizonts produced either uninucleate or multinucleate merozoites. Mature uninucleate merozoites evidently left the schizonts and penetrated new intestinal cells about 4 days after inoculation. Stages of transformation into trophozoites similar to those described for first-generation merozoites were seen. Formation of merozoites was similar to that observed in the second-generation, except that the lateral connection of merozoites with the residual body was not observed. The multinucleate merozoites underwent two types of development. Some remained in the parasitophorous vacuole in which they were formed and developed into third-generation schizonts in situ. Others left the schizont, entered new cells and formed small schizonts. The multinucleate merozoites had merozoite anlagen, including the anterior portion of the inner membrane complex of the third-generation merozoites, and such anlagen were observed in some multinucleate meromoite development on the 4th and 5th day after inoculation.

Download

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .