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A trophozoite (G. trope, nourishment + zoon, animal) is the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing Plasmodium falciparum and those of the Giardia group. [1] The complementary form of the trophozoite state is the thick-walled cyst form. They are often different from the cyst stage, which is a ...
A Giardia trophozoite, drawn by Vilém Lambl and published in 1859 Drawings of a Giardia trophozoite and cyst by Charles E. Simon in 1921. The first likely description of Giardia was in 1681 by Antonie van Leeuwenhoek, who in a letter to Robert Hooke, described "animalcules" resembling Giardia trophozoites in his stool.
A trophozoite (G. trophē, nourishment + zōon, animal) is the activated, intracellular feeding stage in the apicomplexan life cycle. After gorging itself on its host, the trophozoite undergoes schizogony and develops into a schizont, later releasing merozoites.
About 40 species have been described, but most of them are probably synonyms. [11] Currently, five to six morphologically distinct species are recognised. [12] Giardia duodenalis (=G. intestinalis, =G. lamblia) infect humans and other mammals, G. microti infects voles, G. muris is found in other mammals, G. ardeae and G. psittaci in birds, and G. agilis in amphibians. [4]
A duodenal biopsy may incidentally detect Giardia organisms, as in this H&E stained sample. [33] According to the CDC, the detection of antigens on the surface of organisms in stool specimens is the current test of choice for diagnosis of giardiasis and provides increased sensitivity over more common microscopy techniques. [34]
These cysts on reaching the terminal ileum region of the gastrointestinal tract give rise to a mass of proliferating cells, the trophozoite form of the parasite, by the process of excystation. [22] Symptoms of this infection include diarrhea with blood and mucus, and can alternate between constipation and remission, abdominal pain, and fever.
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Close to the center is a schizont and on the left a trophozoite. Ring forms in red blood cells (Giemsa stain) P. falciparum does not have a fixed structure but undergoes continuous change during the course of its life cycle. A sporozoite is spindle-shaped and 10–15 μm long. In the liver it grows into an ovoid schizont of 30–70 μm in diameter.