Microscopy

A	B

A, B:  Eggs of Hymenolepis diminuta.  These eggs are round or slightly oval, size 70 - 85 µm X 60 - 80 µm, with a striated outer membrane and a thin inner membrane. The space between the membranes is smooth or faintly granular.  The oncosphere has six hooks.  There are no polar filaments extending into the space between the oncosphere and the outer shell.  Image A contributed by the Georgia Department of Public Health.

C	D

E	F

C-F:  Eggs of Hymenolepis nana.  These eggs are oval and smaller than those of H. diminuta, with a size range of 30 to 50 µm.  On the inner membrane are two poles, from which 4-8 polar filaments spread out between the two membranes.  The oncosphere has six hooks.

G	H

G, H:  Eggs of H. nana in a trichrome-stained stool specimen.  Although trichrome is not the preferred method for observing helminth eggs, they can be detected this way.  The eggs are distorted, probably due to the zinc polyvinyl alcohol (PVA) used for preserving specimens for trichrome stain.  Images courtesy of the Oregon State Public Health Laboratory.

I	J

I:  Cross-sections of mature proglottids of H. nana stained with hematoxylin and eosin (H&E), taken at 100x. Note the craspedote (overlapping) proglottids.
J:  Higher magnification of the eggs in Figures I, taken at 1000x oil magnification.  Hooks do not stain with H&E but are refractile and may be visible in stained specimens with proper adjustment of the microscope.  Polar filaments are visible in the egg in the upper right quadrant of the image.

Macroscopic (gross) observations

K

K:  Three adult Hymenolepis nana tapeworms.  Each tapeworm (length: 15 to 40 mm) has a small, rounded scolex at the anterior end, and proglottids can be distinguished at the posterior, wider end.  Image contributed by the Georgia Division of Public Health.