Entamoeba coli

Entamoeba histolytica and Entamoeba coli. Cysts in formalin-preserved feces (iodine stain, high power). Cysts of both species lie adjacent to each other. The mature cyst of E. coli is much larger with six or seven nuclei visible in the cytoplasm; the smaller E. histolytica cyst appears to be immature with only a single, larger nucleus containing a clearly visible punctate karyosome.