Entamoeba polecki is a non-pathogenic ameba associated with pigs. The cysts measure 9 to 25 µm and have a large nucleus comprising up to 1/3 of the diameter of the cyst. Cysts are usually uninucleate, but may rarely be binucleate. They have the typical "Entamoeba-type" nucleus and chromatin pattern ('dot and ring'), with a small to large karyosome (central or eccentric location) and light-to-heavy peripheral chromatin. One of the most notable features of the cyst is the presence of numerous variably-sized chromatoid bodies, which may be small to large and have round or splintered ends (see examples below).
The trophozoites measure 10 to 25 µm in greatest dimension are often rounded. They possess a single nucleus (often distorted and irregularly-shaped), with a small to minute centrally-located karyosome. In contrast to the cysts, the peripheral chromatin is usually uniform and delicate. The cytoplasm is commonly vacuolated with a hyaline border, and blunt pseudopodia may be seen.
