[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

CHAPTER 3 The Amebas
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Cytoplasm
No peripheral
chromatin
“Blotlike”
karyosome
Small vacuole
(may contain bacteria)
Pseudopod
A
Size range: 5-12 m
B
Average size: 7-10 m
FIGURE 3-14 A, Endolimax nana trophozoite. B, Endolimax nana trophozoite. (B from Forbes BA, Sahm DF,
Weissfeld AS: Bailey & Scott’s diagnostic microbiology, ed 12, St Louis, 2007, Mosby.)
No peripheral chromatin
“Blotlike” karyosome
Cytoplasm
Cyst wall
A
Size range: 4-12 m
B
Average size: 7-10 m
FIGURE 3-15 A, Endolimax nana cyst. B, Endolimax nana cyst (trichrome stain, ×). (B from Mahon CR, Lehman DC,
Manuselis G: Textbook of diagnostic microbiology, ed 4, St Louis, 2011, Saunders.)
these trophozoites is granular and vacuolated,
and usually contains bacteria.
Cysts. The spherical, ovoid, or ellipsoid cysts
of E. nana typically measure 7 to 10 µm in size
(Fig. 3-15; Table 3-10). Some cysts may measure
a mere 4 µm, whereas others may be as large as
12 µm. Although there may be one to four nuclei
in an E. nana cyst, the most commonly seen form
is the mature cyst that contains four nuclei. The
structures of these cyst nuclei are basically identical
to those seen in the trophozoite—a large blotlike
karyosome, usually centrally located, and
the absence of peripheral chromatin. The cytoplasm
of E. nana cysts may contain granules of
chromatin material or nondescript small oval
masses. Chromatoid bars, such as those often
seen in the Entamoeba spp. cysts, are not present.
A diffuse glycogen mass may be present in young
cysts.
Laboratory Diagnosis
As with other intestinal amebas discussed in this
chapter, the laboratory diagnostic technique of