Endogenous stages of Eimeria arvicanthi infecting the field rat Arvicanthis niloticus niloticus from Egypt.

The endogenous stages of Eimeria arvicanthi were studied after experimental infection with pure strain in the rat Arvicanthis n. niloticus. The prepatent period was 5 days, while the patent period extended to the 11th day p.i. Two asexual generations were determined in the epithelial cells of the upper part of the colon, while the sexual one was found in the crypts of Lieberkühn. Schizonts of the 1st generation were found 60 hrs p.i., measuring 9 X 4 microns and contained 4-8 merozoites, however those of the 2nd generation were found at 96 hrs p.i., measured 14 X 10 microns and contained 8-12 merozoites. Gamonts were firstly recorded at 108 hrs p.i., after growth they differentiated and gave rise to gametes. Macrogametes were 19 X 17 microns with large nuclei and wall-forming bodies in their cytoplasm. Microgamonts (14 X 11 microns) were irregular in shape and after many nuclear divisions produce many microgametes. Eimeria arvicanthi was pathogenic and about 60% of the experimentally infected rats with 3-5 X 10(5) sporulated oocysts were died till the 9th day p.i.