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Table of Contents > Protozoans > Amoeba > Entamoeba coli morphology > Entamoeba coli artifacts

Entamoeba coli

The ability to identify amoeba based on nuclear structure in iodine wet mount preparations is limited. Cysts of the amoeba are usually granular. Cysts of the mature pathogenic E. histolytica contain four nuclei while those of the non-pathogenic E. coli contain up to eight nuclei.
102 - E coli troph The single nucleus of the trophozoite is often visible in unstained preparations with the non-compact karyosome that is eccentrically located.

Sometimes the nuclei may contain a central karyosome with uniform, peripheral chromatin and may be confused with the pathogenic Entamoeba histolytica, as in the E. coli at left.

A distorted Giardia cyst is also evident in this field.

29 E coli
28 - E. coli cyst

Immature E. coli cysts containing four or fewer of the eight nuclei may be difficult to distinguish from E. histolytica.

But not so in these wet preparations where 5-7 nuclei can be seen.

100 - E coli cyst

Sometimes uninucleate cysts can also be seen with a large central glycogen vacuole pushing the nucleus to the margin of the cyst. Note the eccentrically placed karyosome.

A dark Giardia cyst is also evident in this phase mount.

30 - E coli cyst and dark Giardia cysts
E. coil trophs - Trichrome x 1000
E.coli trophozoite
Trichrome stain x 1000
E. coli troph - Trichrome x 1000

These two trophozoites demonstrate some typical features of the parasite.

  • karyosomes are eccentrically positioned
  • perpheral chromatin is irregularly distributed
  • cytoplasm is vacuolated

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