[Elizabeth_Zeibig]_Clinical_Parasitology__A_Practi(z-lib.org)

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CHAPTER 12 Artifacts and Confusers
Size range: 12-150 m in diameter
FIGURE 12-10 Plant material.
FIGURE 12-12 Fungal elements.
FIGURE 12-11 Epithelial cell.
FUNGAL ELEMENTS
Fungal elements may be similar to the size and
shape of protozoan cysts (Fig. 12-12). The lack
of interior structures easily distinguishes these
artifacts from parasitic forms.
Quick Quiz! 12-4
Plant material differs from a helminth eggs in that
plant material may have peripheral pseudocilia.
(Objective 12-1)
A. True
B. False
Quick Quiz! 12-5
Which parasite may be confused with epithelial
cells because of their similar size and shape? (Objective
12-1)
A. Helminth eggs
B. Plasmodium spp.
C. Amebic trophozoites
D. Dientamoeba fragilis
EPITHELIAL CELLS
Epithelial cells often show a striking resemblance
to amebic trophozoites in size and shape (Fig.
12-11). In addition, epithelial cells have a single
nucleus and often show a distinct cell wall, just
like those of the amebic trophozoites. Epithelial
cells lack the typical amebic trophozoite interior
structures. For example, the cytoplasm of epithelial
cells is usually smooth and contains no inclusions.
The large epithelial cell nucleus, however,
may consist of a large chromatin mass that
resembles a nucleus.
STARCH CELLS
Round to irregular round-shaped starch cells
(Fig. 12-13), also referred to as starch granules,
measure less than 10 µm and may appear at first
glance to be protozoan cysts, particularly those
of E. hartmanni and E. nana (both measure 5 to
12 µm). These cells are readily differentiated
from parasitic forms because they lack internal
structures. A nondescript mass located inside the
cell is often present and may resemble a nucleus.
Further investigation of this structure reveals