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[Endolimax nana] [Entamoeba coli] [Entamoeba hartmanni] [Entamoeba polecki] [Iodamoeba buetschlii]

Entamoeba hartmanni is often called a "small E. histolytica" because these two species share many morphological characteristics, except their size.  Trophozoites of E. hartmanni measure usually 8 to 10 µm (range 5 to 12 µm) and are smaller than those of E. histolytica (10 to 60 µm).  The trophozoites of E. hartmanni have one nucleus with fine peripheral chromatin and a small, often centrally located karyosome.  The cytoplasm is finely granular.

A	B

A: Line drawing of an E. hartmanni trophozoite.
B: E. hartmanni trophozoite stained with trichrome and measuring 8.1 µm.  Image contributed by the Kansas Department of Health and Environment.

C	D

C, D:  E. hartmanni trophozoites stained with trichrome.  Note that in C, the trophozoite has ingested a yeast not an erythrocyte.  Ingestion of erythrocytes is pathognomonic of E. histolytica.

E

E: E. hartmanni trophozoite stained with trichrome.  A Blastocystis hominis cyst-like form is in the upper right corner of the image.