Encystation of axenically grownEntamoeba histolytica: Effect of bacterial endotoxins, starch and epinephrine

Abstract

Axenically grown trophozoites of Entamoeba histolytica, starch fed and toxin treated, when incubated in a minimal medium containing epinephrine and theophylline at 33° ± 1°C were transformed to a round form with a thick outer wall; in contrast, the untreated cells died. These round bodies or “precysts” hatched to the trophic form when transferred to fresh growth medium. Formation of round bodies occurred even in the absence of cysteine but they were not mature and readily disintegrated.