Dr. Holló Ferenc szerk.: Parasitologia Hungarica 3. (Budapest, 1970)

The single schizogonic stage of E.maxima

,as described by BHATIA and PANDE (1968), seems to be an exception. The sporozoites of E.tenella finally invade the caecal epithelial cells (McL AREN and PAGE,

1968; MclAREN

,1969). Eor a certain time they are intimately connected with the host cell's cytoplasm, as their limiting membranes contact directly.The roundedoff trophozoites are already enclosed in a vacuole

.The schizonts are surrounded by a unit membrane. In young schizonts the endoplasmic reticulum increases and several nuclei appear scattered in the schizont body. The merozoites separate by evagination of the nuclear protrusions

.In light micrographs

,the conoid appears as a pale eosinophilic detail at the tapering end of the developing merozoites. Mature merozoites remain for a given time attached to the schizont by one end. They seem to be held by a ring-like structure.In the pale cytoplasmic sectors of juvenile merozoites, thready structures (mitochondria?) surrounded by a double membrane are seen by electronmicroscopy

. Immature merozoites are characterized also by a round vacuole, surrounded by an electron dense membrane. This vacuole disappears by the time of maturation. After the maturation of the merozoites,only a small portion of cytoplasm is retained in the schizont as a residual body. The latter contains linear mitochondria, lipid inclusions and elements of endoplasmic reticulum. The parasitophorous vacuole is lined with a double limiting membrane. The vacuole increases parallelly with the growth of the parasite so that in the gametogonic stage it is hardly recognized as such. The xenon (parasite

+ host cell complex) tends to separate from the organism and in this phase it should be regarded a pseudocyst. According to TYZZER, the E.tenella xenons,particularly from the second generation on, sink deeply under the epithelial layer owing to the pressure of the epithelial cell row. This seems to account for the subepithelial location of xenons in most histological preparations. Gill and RAY (1957) found that the sporo-