STRUCTURE OF SARCOCYSTIS NEURONA SARCOCYSTS

The ultrastructure of Sarcocystis neurona sarcocysts was studied from muscle of an experimentally infected cat. The cat was killed 144 days after being fed sporocysts from a naturally infected opossum. Sarcocysts were microscopic, up to 700 μm long, and up to 50 μm wide. By light microscopy, the sarcocyst wall was 1–2 μm thick. Ultrastructurally, the sarcocyst wall consisted of numerous villar protrusions. The villar protrusions were up to 2.8 μm long and 0.4 μm wide, with a tapered end. Microtubules extended from the tip of the villus to the base and occasionally extended deep into the granular layer. The granular layer was ∼0.5 μm thick. Longitudinally cut bradyzoites were 5.2 by 1.2 (4.8–6.5 by 1.0–1.3) μm in size. Micronemes in bradyzoites were numerous and located in the anterior ⅓ of the conoidal end.