Entamoeba hartmanni

This photomicrograph of a trichrome-stained specimen revealed the presence of an Entamoeba hartmanni trophozoite (arrow). E. hartmanni is classified as a nonpathogenic intestinal protozoan organism. The trophozoites of E. hartmanni usually measure 5 to 15 m. These trophozoites possess a single nucleus which contains a small compact centrally or eccentrically located karyosome and thin and uniform peripheral chromatin. Nuclei are usually not visible in unstained specimens. The cytoplasm is finely granular. Trophozoite motility is described as non-progressive. CDC/Dr Mae Melvin 1977. (Photo by: CDC/IMAGE POINT FR/BSIP/Universal Images Group via Getty Images)