LIGHT AND ELECTRON-MICROSCOPY STUDY OF FIRST GENERATION DEVELOPMENT OF EIMERIA-PAPILLATA (APICOMPLEXA, EIMERIIDAE) IN POLARIZED MDCK-CELLS IN-VITRO

The early development of Eimeria papillata (Apicomplexa) was studied i n vitro using light and electron microscopy. The first developmental s tages observed were elongated, sporozoite-shaped schizonts with two nu clei and two refractile bodies which appeared 17 hours p.i.; the schiz onts retained this shape until the 8-nuclei-stage. At 23 hours p.i. th ey had changed into a spherical shape, the refractile bodies had multi plied and the development of merozoites was observed. Each merozoite o f the first generation contained two refractile bodies. An improved me thod for in vitro cultivation of Eimeria in polarized host cells and s ubsequent fine structural investigation is described.