Schizogony and Gametogony of Eimeria tenella in Cell Cultures

Abstract

SUMMARY Schizogony and gametogony of Eimeria tenella occurred in primary cultures of embryonic chicken kidney cells grown in Eagle's minimum essential medium supplemented with 10% newborn calf serum and incubated at 40 to 41 C. Although some sporozoites penetrated cells within minutes after they were inoculated onto the cell monolayers, invasion of cells continued for at least 24 hours. Mature first-generation schizonts, containing merozoites approximately 7 μ long, usually appeared between 48 and 72 hours after cultures were inoculated, and mature second-generation schizonts, with merozoites approximately 14 μ long, were seen after 96 hours. Since development was not synchronous, all stages of maturation from sporozoites to second-generation merozoites were seen at this time. Third-generation schizonts and immature gametocytes were recognized in the cultures after 144 hours of incubation; mature gametes and oocysts formed between 160 and 200 hours. In unfixed cultures, sporozoites and merozoites moved in either direction when intracellular. Developing schizonts constantly changed shape and sometimes migrated within their host cells. Activation of merozoites within a mature schizont was nearly instantaneous, although release from the elastic schizont membrane was gradual.