Manual of basic techniques for a health laboratory - libdoc.who.int

116 Manual of basic techniques for a health laboratoryFig. 4.21 Trichomonas hominis trophozoitesFig. 4.22 Chilomastix mesnili trophozoitesCytoplasm: greyish-green with:— towards the tapered end: a distinct spiral marking, around which the flagellateturns (figure-of-eight)— near the rounded end: a mouth-like cleft (faintly visible cytostome).Nucleus: one nucleus, easily visible in unstained preparations.Identification of motile forms of ciliatesBalantidium coli (rare) (Fig. 4.23)Size: about 50mm.Shape: oval, with one pole more rounded than the other.Cilia: covered with many small cilia, which move with rapid strokes.Motility: moves very rapidly in stools, crossing the field in a definite direction andsometimes turning in circles.Cytoplasm: transparent.Nuclei: a large kidney-shaped nucleus next to a small round nucleus.“Mouth”: the cytostome; a sort of mouth that contracts and expands, drawing incell debris.Important: If stools are left exposed to the air, without a lid, organisms of the infusoriatype may fall on to them from the atmosphere. These may be confused withBalantidium coli.