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[Blastocystis hominis]

Blastocystis hominis appear as spherical to oval cyst-like structures.  They vary widely in size (5 to 30 µm; usual range 8 to 10 µm), and typically consist of a central body, or "vacuole," surrounded by a thin rim of cytoplasm containing up to six nuclei.  The vacuoles stain variably from red to blue in trichrome stain, which is preferred to wet mounts as the organisms can be overlooked as debris.

A	B

A, B: B. hominis cyst-like forms in wet mounts stained in iodine.