Entamoeba histolytica

• Immature, uninucleated cyst in stool specimen, Trichrome stained
• Spherical or ovoidal in shape, 12-20 micrometer in diameter
• Cyst wall not stained
• Greenish cytoplasm contains reddish-purple colored,
  cigar-shaped chromatoid bars
• Single nucleus contains reddish, concentric karyosome, and
  peripheral chromatin evenly distributed