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[Hymenolepis diminuta] [Hymenolepis nana]

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.

A	B

A, B:  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.