9. Trophozoites, unstained Not characterictic
Trophozoites, stained Diagnostic: nucleus with large
central karyosome surrounded
by a ring of small chromatin
granules; or nucleus structure
as in cyst
Cysts, unstained Suggestive: large refractile body
in cytoplasm; single nucleus
Cysts, stained Diagnostic: basket nuclei or
nuclei as in trophozoite; large
glycogen vacuole
18. The most common of the smaller
intestinal amebae
usually encountered with about the same
frequency as in E. coli
Size range for both trophozoites and cyst
is similar to that of E. hartmanni [(usual
size, 4-12 µm) and cyst forms (usual
size, 5-10 µm)], thus makes confusion in
unstained preparations
Epidemiology is cosmopolitan
Colonizes the colon
19.
20.
21.
22. Trophozoites, unstained Not charateristic
Trophozoites, stained Diagnostic: a nucleus with large
karyosome, generally with little or
no peripheral chromatin
Suggestive: Ovoid
Cysts, unstained Suggestive: Ovoid
Cysts, stained Diagnostic: 4 nuclei with large
karyosome and little or no
peripheral chromatin
23. Trichrome stain
The nuclei in this mature, quadrinucleated cyst
have a large karyosome surrounded by a clear
halo; peripheral chromatin is absent.
24. Wet mount
examination of SAF-
fixed specimen
The nuclear characteristics of this trophozoite
are clearly visible
Trophozoites may be very difficult to recognize in an unstained concentrate as the nucleus is all but invisible. The cyst is more obvious because of its large vacuole which, as above, appears as a void within the cell. Iodine can be added to stain the glycogen, making it more visible with the production of a dark brown colour.
