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. Trophozoites generally measure 5 to 15 m. These trophozoites have a single nucleus which contains a small, compact, central or eccentric karyosome, and thin, 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