Ulcers with slightly undermined edges are seen in this image of colonic amebiasis. The motile form of E. histolytica, the trophozoite, lives in the lumen of the large intestine, where it multiplies and differentiates into the cyst, the resistant form responsible for the transmission of the infection. Cysts are excreted in stools and may be ingested by a new host via contaminated food or water. The parasite excysts in the terminal ileum, with each emerging quadrinucleate trophozoite giving rise to eight uninucleated trophozoites. Trophozoites may invade the colonic mucosa and cause dysentery and, through spreading via the bloodstream, may give rise to extraintestinal lesions, mainly liver abscesses.