Iodamoeba buetschlii is one of several non-pathogenic amebae that can be found in human stool specimens. Both trophozoite and cyst forms exist. The cysts, as shown here, are round to oval and measure 5 to 20 micrometers in greatest dimension. On permanent-stained preparations (e.g. trichrome), the nucleus is similar to that of the trophozoite with a large "blot-like" karyosome. Achromatic granules may or may not be present around the karyosome. Cysts characteristically have a large compact glycogen-containing vacuole which stains deeply with iodine on wet mount preparations. On permanent-stained preparations, the vacuole often appears as a well-defined, empty-appearing mass.