Parasitology Artifacts - Entamoeba histolytica

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

Entamoeba histolytica

The trophozoites may range in size from 10-60 mm.

The single nucleus may not be visible in unstained preparations.

92-E. histolytica trophozoites - phase contrast x400

2-25 E. histolytica trophozoite - phase contrast x 400

The nucleus has a small compact karyosome that is usually centrally located but maybe eccentric.

The peripheral chromatin typically is finely granular and is distributed evenly over the inner surface of the nuclear membrane.

Mature cysts are spherical and contain four nuclei, the usual size ranges from 12-15 mm. Except for their smaller size, the structures of the nuclei in the cysts are similar to those in the trophozoites.

Nuclei are visible in wet preparations and the glycogen present in the mature cyst is usually diffuse.

95-Entamoeba histolytica cyst - phase contrast x 400

Entamoeba histolytica cyst - phase contrast x 400

In young cysts the glycogen is a discrete mass normally pushing the nucleus to one side and contains a spread out karyosome. Immature cysts like these can be easily confused with E. coli cysts which maybe the same size.

Immature cysts may contain one or two nuclei as seen in these three cysts.

Entamoeba histolytica cyst - trichrome x 1000

Entamoeba histolytica cyst
Trichrome stain x1000

A binucleate cyst containing a chromatoidal body is seen in this field. The small eccentric karyosome is not very evident.

Entamoeba histolytica troph - trichrome x 1000

Entamoeba histolytica trophozoite
Trichrome stain x1000

Note the characteristic nuclear structure of this amoeba. ie. a discrete, small karyosome and evenly distributed peripheral chromatin.

Small vacuoles are present in the cytoplasm.

View E. histolytica artifacts