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An organelle in certain protozoans, especially ciliates, consisting of filamentous fibers that are discharged suddenly.

trich′o·cys′tic adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Zoology) any of various cavities on the surface of some ciliate protozoans, each containing a sensory thread that can be ejected
ˌtrichoˈcystic adj
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈtrɪk əˌsɪst)

a small sac in certain protozoans that contains a hairlike stinger.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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The ciliary patterns on the surface of the trophont are the basis for species identification among apostome ciliates (Chatton and Lwoff 1935), though other characteristics can be used to identify whether a ciliate is an apostome or not, including internal structures; especially trichocysts, secretory dense bodies, a rosette, and membrane organelles (Bradbury 1966, 1973, Landers 1991a, 1991b, Landers et al.
Another useful application of paramecia in a lab is stimulating them to release trichocysts. Trichocysts are carrot-shaped organelles of unknown function that are released in response to certain stimuli.
Some, such as Cochlodinium, form rod-shaped bodies (trichocysts) of different sizes that can be rapidly extruded and form sticky filaments (possibly also poisonous) that stick to and harm the gills of fish.
Extrusomes are organelles common to most ciliates and dinoflagellates (Bouck and Sweeney, 1966; Dodge and Greuet, 1987; Gortz, 1988), and also found in some other taxa, that explosively release toxicysts, trichocysts, or nematocysts from the cell surface.