ULTRASTRUCTURAL OBSERVATIONS ON THE 3RD-GENERATION MEROZOITES OF EIMERIA-TENELLA IN CHICKS

The fine structure of the third-generation merozoites of Eimeria tenel la is described from caecal enterocytes of chicks 120 h after experime ntal infections. The merozoites conformed to the general eimerian patt ern except that they were bounded by two unit membranes. Young gamonts also conformed to the general eimerian pattern, and were limited by a n outer unit membrane and an interrupted inner membrane. Enterocytes i nvaded by third-generation merozoites showed a loss of microvilli and large blebs that protruded into the caecal lumen. These blebs appeared to contain only cytoplasm and not any cell organelles.