trichocyst

trichocyst

[trik-uh-sist]
noun Zoology.
an organ of offense and defense embedded in the outer cytoplasm of certain protozoans, consisting of a small elongated sac containing a fine, hairlike filament capable of being ejected.

Origin:
1850–55; tricho- + cyst

trichocystic, adjective
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World English Dictionary
trichocyst (ˈtrɪkəˌsɪst)
 
n
any of various cavities on the surface of some ciliate protozoans, each containing a sensory thread that can be ejected
 
tricho'cystic
 
adj

Collins English Dictionary - Complete & Unabridged 10th Edition
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Encyclopedia Britannica
Encyclopedia

trichocyst

a structure in the cortex of certain ciliate and flagellate protozoans consisting of a cavity and long, thin threads that can be ejected in response to certain stimuli. Trichocysts may be widely distributed over an organism or restricted to certain areas (e.g., tentacles, papillae, around the mouth). There are several types. Mucoid trichocysts are elongated inclusions that may be ejected as visible bodies after artificial stimulation. Filamentous trichocysts in Paramecium and other ciliates are discharged as filaments composed of a cross-striated shaft and a tip. Toxicysts (in Dileptus and certain other carnivorous protozoans) tend to be localized around the mouth. When discharged, a toxicyst expels a long, nonstriated filament with a rodlike tip, which paralyzes or kills other microorganisms; this filament is used to capture food and, presumably, in defense

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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