Entamoeba histolytica

Entamoeba histolytica. Cysts in fecal smear (trichrome stain, oil immersion). One cyst contains a large glycogen vacuole; its nucleus, characteristically large in young cysts, is pushed to one side and contains a diffuse, "spread-out" karyosome. Immature cysts like these are sometimes confused with uninucleate cysts of E. coli, which may be similar in size and morphology. The other immature cyst in the field contains numerous rounded chromatoid bodies that partially obscure the glycogen vacuole.