Balantidium coli trophs
is the largest intestinal protozoan of humans. Acquired by ingestion of cysts from the stool of an infected person, Balantidium causes recurrent diarrhea alternating with constipation. These pathogens move by means of cilia (short hair-like filaments) and thus are in the class Ciliata.
Balantidium possess two nuclei: a micronucleus and a distinctive kidney-shaped macronucleus. A funnel-shaped cytostome is sometimes visible. The outside of Balantidium trophozoites ("trophs") is covered with cilia for motion.
The troph stage of Balantidium is somewhat oval, while the cyst is a circle.
Diagnosis depends upon finding Balantidium cysts or trophs in the stool. Trophs are shown in these images.
Click on each image to see the enlarged version.
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| 1. troph 400 X | 2. troph 400 X | 3. troph 400 X | 4. troph 400 X | 5. troph 400 X |
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| 6. troph 1000 X | 7. troph 1000 X | 8. troph 1000 X | 9. troph 1000 X | 10.troph 1000 X |
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