Electron microscopic study of the cyst of the sarcosporidian, Sarcocystis ovifelis

Cysts of S. ovifelis, examined from the sheep oesophagus muscles have been shown to be covered by a cyst wall made of a primary and a secondary envelopes. Within the cyst, three morphologically different cell types are distinguished: metrocytes, merozoites, and interstitial cells. The latter have been first discovered for the genus Sarcocystis, in addition to earlier literature evidence of their availability in cysts of the genus Frenkelia.