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.
(The complement of the trophozoite state is the thick-walled
cyst
A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...
form).
Life cycle stages
Trophozoite and cyst stages are shown in the life cycle of ''
Balantidium coli
''Balantidium coli'' is a parasitic species of ciliate alveolates that causes the disease balantidiasis. It is the only member of the ciliate phylum known to be pathogenic to humans.
Morphology
''Balantidium coli'' has two developmental stag ...
'' the causative agent of
balantidiasis
Balantidiasis is a protozoan infection caused by infection with '' Balantidium coli''.
Symptoms and signs
Usually asymptomatic in immunocompetent individuals, but the symptoms of balantidiasis include:
* Intermittent diarrhea
* Constipation
* Vom ...
.
In the
apicomplexan life cycle
Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism is ...
the trophozoite undergoes schizogony (asexual reproduction) and develops into a
schizont
Apicomplexans, a group of intracellular parasites, have life cycle stages that allow them to survive the wide variety of environments they are exposed to during their complex life cycle. Each stage in the life cycle of an apicomplexan organism i ...
which contains
merozoites.
The trophozoite life stage of ''
Giardia'' colonizes and proliferates in the small intestine. Trophozoites develop during the course of the infection into cysts which is the infectious life stage.
References
Parasitology
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