Entamoeba histolytica cysts
is the single-celled protozoan that causes amoebic dysentery. Infection may ensue after ingestion of food or water that contains Entamoeba cysts. Because it moves with pseudopods , Entamoeba is in the class Sarcodina . Cysts of Entamoeba histolytica are shown at 1000 X magnification in fecal material. Each Entamoeba cyst is a nearly perfect circle, whereas Entamoeba trophozoites (trophs) will have an irregular shape. Cysts and trophs in the stool are used for diagnosis. Each Entamoeba may have up to four nuclei. The presence of a karysome (a dark staining circular structure within the nucleus), and/or chromatin body (cigar-shaped structure in the cytoplasm) may help identify an organism as Entamoeba.
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