Balantidium coli trophozoite (stained). Note the large bean-shaped macronucleus, fine layer of cilia surrounding the organism, and mouth-like structure. Trophozoites are typically seen in direct fecal smears.
Balantidium coli cyst (stained). Note the large macronucleus.
Balantidium coli cyst (not stained). In non-stained specimens the large, bean-shaped macronucleus is not easily observed.
Cyst of Buxtonella sulcata. A ciliate found in the colon of cattle, Buxtonella sulcata exists in cyst form outside the host. The ciliated form resembles Balantidium coli in swine. Pathogenesis is minimal and the presence of cysts in feces is considered an incidental finding.
Ichthyophthirius multifiliis trophont cross section in fish gill. Ich has two basic phases to its life cycle, the free-living stage which includes the infective tomites and cystic tomocysts, and the parasitic phase, consisting of feeding and reproducing trophonts. Trophonts are the stage found on skin scrapings of affected fish.
Trophont of Ichthyophthirius multifiliis from the skin of a fish. Trophonts can range greatly in size, but have a charcteristic horseshoe shaped macronucleus, seen as a pale structure in this image, a cilliated buccal cavity near the anterior end, and an oval to round body.