Dr. Holló Ferenc szerk.: Parasitologia Hungarica 3. (Budapest, 1970)
etc.)' With, the growth of the macrogametocyte, its nucleus and the enclosed nucleolus tend to become more and more conspicuous. Later on, granules appear in the cytoplasm which play a role in forming a wall around the fertilized macrogamete (zygote). First the so-called wall-forming or membraneceous bodies can be identified already in very early macrogametes, whereas the dark bodies (polysaccharide material) develop only later. They may be denoted according to SCHOLTYSECK' s proposal as wall-forming bodies I and II. SCHOLTYSECK, HAMME and ERNST (1966) believe that these bodies develop inside a large bladder of endoplasmic reticulum, but McLAREN (1969) failed to verify this concept. MclAREN stated that the earliest wall-forming bodies were spirals freely located in the cytoplasm. The larger wall-forming bodies are membrane-bound and sit in a vacuole. In a more advanced stage of gametogony, dark bodies appear in increasing numbers in the macrogamete ' s cytoplasm.They are very likely the electronmicroscopic counterparts of the structures known light microscopically as plastic granu±a (REICH, 1913; CHEISSIN, 1958, etc.). According to PATTILLO and BECKER (1955), they consist of mucoprotein,mucopolysaccharide or glycoprotein. As the E.tenella macrogamete tends to become more and more ovoid, the dark bodies tend to arrange peripherally, until they merge to form the middle layer of the cyst wall. The outer layer of the wall is derived from the zygote's outer limiting membrane, while the inner layer seems to be constituted by the wall-forming bodies. Indeed, these bodies disappear as soon as the inner layer is completed. The duration of endogenous development that is, the time elapsing between the ingestion and shedding of oocysts, varies with the species and is, therefore, a species characteristic. The endogenic phase of the cycle has been called the prépaient period - the correctness of this term may be disputed - and the phase beginning with the appearance of oocysts in the faeces the patent period. With the Eimeriae of gallinaceous birds the
