CYTOCHEMICAL ELECTRON MICROSCOPY ON POLYSACCHARIDE GRANULES IN THE ENDOGENOUS FORMS OF EIMERIA BRUNETTI

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Abstract
Endogenous stages in the life cycle of E. brunetti were tested for polysaccharide material by EM cytochemistry using the periodic acid-thiocarbohydrazide-osmium tetroxide (PATO)-method. The parasites were observed within the epithelial cells of the small intestine of infected domestic fowls. Two types of granules reacted positively for polysaccharide. The 1st was large, about 500 nm .times. 250 nm. These granules resembled polysaccharide granules reported for other coccidian parasites. They were observed in mature merozoites, macrogamonts and developing oocysts. The 2nd was smaller (15-30 nm in diameter), and was only observed at the periphery of the residual cytoplasmic mass of mature microgamonts. It was more similar in appearance to metazoan glycogen than the former. Since the PATO-method does not differentiate between different polysaccharides it cannot be proven if these granules contain glycogen. The WFB[wall forming body] I of the macrogamete and the outer layer of the oocyst wall gave a slight positive reaction, but examination of controls showed that this reaction was not specific.