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In this article we will discuss about Balantidium Coli:- 1. Habit and Habitat of Balantidium Coli 2. Structure of Balantidium Coli 3. Reproduction 4. Transmission of Disease.
Habit and Habitat of Balantidium Coli:
Balantidium Coli is largest protozoan of the human intestine inhabits the caecum and ascending colon.
Structure of Balantidium Coli:
The body of Balantidium Coli is egg-shaped (Fig. 10.46A). The anterior end is pointed and the posterior end is round. The length of the body is 68-134 micra and width is 44-89 micra. The outer limiting surface, pellicle is rigid. Cilia are embedded in longitudinal rows. Near the middle of the frontal extremity the pellicle bears a funnel-shaped depression, called peristome. The peristome is provided with an aperture, the cytostome at its bottom.
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The cilia, lining the peristome are larger than the rest of the body cilia. There are two constantly occurring contractile vacuoles and a number of food vacuoles. The cytopyge is an inconspicuous aperture situated at the rear. Embedded in the cytoplasm there are the kidney-shaped macronucleus and a very small, rounded micronucleus hidden within the concavity of the macronucleus.
The trophic forms change to cystic forms (Fig. 10.46B). The cysts are nearly spherical, measuring about 55 x 55 sq. micra and the walls are thick. The individuals during encystment retain cilia and are motile.
Fig. 10.46: Balantidium Coil (after Kudo). A. trophozoite. B. Cyst.
Reproduction in Balantidium Coli:
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Asexual reproduction occurs by transverse fission. It is preceded by mitotic division of the micronucleus and amitotic division of the macronucleus.
Sexual reproduction occurs by conjugation. The process resembles that of Paramoecium in minute details.
Transmission of Disease from Balantidium Coli:
Transmission from one host to another occurs in encysted condition through drinking water and contaminated food.
The specific damages done by Balantidium are not known and no more than one- fifth of the infected subjects experiences symptoms. So some observers prefer to consider it as a commensal.
The Phylum Protozoa include a large variety of forms. The following tables will give a comparative account of some of the important representatives.
