Trichomonas vaginalis: Morphology, Habitat, Nutrition, and Life Cycle

    T. vaginalis is a single-celled, teardrop shaped protist that can grow between five and 20 micrometers wide. Four anterior and one posterior flagella allow T. vaginalis to move. The posterior flagellum is part of the center axostyle, and has a barbwire-like structure. This structure allows the protist to attach to and tear the urethra or vaginal walls, which causes inflammation and aids in speeding and intensifying infection. T. vaginalis has a cell membrane, but lacks a cell wall. Half of the cell body also has an undulating membrane, which helps sweep nutrients into the protist's mouth-like structure, called the cytosome. A visible nucleus is located at the organism's center.

.Leventhal, Ruth, and Russell Cheadle. "Trichomonas vaginalis." Cartoon. Medical Parasitology. 4th ed. Philadelphia: F.A. Davis Company, 1996. 78.

    Parabasalids like T. vaginalis are not free living organisms. They require a human or animal host. T. vaginalis has a worldwide distribution. In men, the organism lives in the urinary tract, most commonly the urethra or prostate, where as in women, it is found in the reproductive tract, usually in the vagina. A healthy vagina is a somewhat acidic environment (pH 3.8-4.2). When pH is thrown off and becomes more basic, if T. vaginalis is present, it can cause infection. T. vaginalis is most successful in an enviroment with pH near 6, however, it is a fairly resilient protist, and can survive about 24 hours in urine, semen, or water.

    Like other parabasalids, T. vaginalis acquires nutrients through cell membrane transport and phagocytosis. The undulating membrane assists in this process. Bacteria, archea, and even parts of the vaginal wall are consumed. Enzymes break down these food sources and convert them to useable energy through glycolysis. T. vaginalis lacks a traditional mitochondria, like all other Excavates. In place of a true mitochondria, there is a reduced form known as a hydrogenosome. Hydrogen gas is a by-product of the hydrogenosomes.

 Reproduction and Life Cycle
    T. vaginalis reproduces asexually through longitudinal fission. The trophozoites (adults) then live in the urinary or reproductive tracts, until they are passed onto their next human host via unprotected sexual contact, where the whole process starts over again. Unlike many other protists, T. vaginalis does not have a cyst stage as part of reproduction.

Public Health Image Library. 14 Jan. 2008. Centers for Disease Control and Prevention. 14 Apr. 2009 <>.