TABLE A10.

Morphology of cyst forms (flagellates)

Species	Size (length [μm])	Shape	No. of nuclei	Other features
Pentatrichomonas hominis	No cyst
Chilomastix mesnili	6–10; usual range, 8–9	Lemon shaped with anterior hyaline knob	1 (not visible in unstained preparations)	Cytostome with supporting fibrils; usually visible in stained preparations
Giardia lamblia (G. duodenalis, G. intestinalis)	8–19; usual range, 11–12	Oval or ellipsoidal	Usually 4 (not distinct in unstained preparations; usually located at one end)	Fibrils or flagella appear longitudinally in unstained cysts; deeply staining fibers or fibrils may be seen lying laterally or obliquely across fibrils in the lower part of the cyst; cytoplasm often retracts from a portion of the cell wall
Enteromonas hominis	4–10; usual range, 6–8	Elongated or oval	1–4 (2 usually lie at opposite ends of the cyst; not visible in unstained mounts)	Resembles E. nana cyst; fibrils or flagella are usually not seen
Retortamonas intestinalis	4–9; usual range, 4–7	Pear shaped or slightly lemon shaped	1 (not visible in unstained mounts)	Resembles Chilomastix cyst; shadow outline of cytostome with supporting fibrils extends above nucleus