Ultrastructural studies of the effects of the ionophore lasalocid on Eimeria tenella in chickens.

The ultrastructural development of Eimeria tenella was studied in experimentally infected chicks fed 90 ppm lasalocid, an ionophorous anticoccidial antibiotic. Drug treatment was timed to target-specific endogenous stages. At 6 h after infection, many sporozoites within the epithelium showed degradation as a result of drug action. Only a few intact sporozoites were seen. The drug caused outer-membrane blistering, large surface swellings and enlarged mitochondria in both first- and second-generation merozoites. No effect on the gamonts was discerned.