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

Cysts of Entamoeba coli are usually spherical, but may be elongated, and measure 10 to 35 µm.  Mature cysts typically have 8 nuclei but may have as many as 16 or more.  Entamoeba coli is the only species in the genus encountered in humans with more than four nuclei in the cyst stage.  The nuclei may be seen in unstained as well as stained specimens.  Karyosomes may be compact or diffuse, and are usually eccentrically located.  Peripheral chromatin is present and is often coarse and granular, and irregularly arranged along the nuclear membrane, but may be more uniform.  The cytoplasm of mature cysts may contain diffuse glycogen.  Chromatoid bodies are seen less frequently than in E. histolytica.  When present, they are usually splinter like with pointed ends and thus different from the chromatoid bodies of E. histolytica, which have rounded ends.

A	B

A: Cyst of E. coli in a unstained concentrated wet mount.  Six nuclei are visible in this focal plane.
B: Cyst of E. coli in a concentrated wet mount stained with iodine. Five nuclei are visible in this focal plane.

C	D

C: Cyst of E. coli in a concentrated wet mount stained with iodine.  Seven nuclei are visible in this focal plane.
D: Cyst of E. coli in a concentrated wet mount stained with iodine. Five nuclei are visible in this focal plane.

E

E: Cyst of E. coli in a concentrated wet mount stained with iodine.  Five nuclei are visible in this focal plane.