Also found in: Medical, Encyclopedia, Wikipedia.
Related to karyosome: excystation


An irregular aggregation of chromatin in the nucleus of a cell not undergoing mitosis.
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.


1. (Biology) any of the dense aggregates of chromatin in the nucleus of a cell
2. (Biology) the nucleus of a cell
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈkær i əˌsoʊm)

any of several masses of chromatin in the reticulum of a cell nucleus.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
Mentioned in ?
References in periodicals archive ?
There is one nucleus with a large blot-like karyosome and no peripheral chromatin.
Karyosome A structure within the nuclue of amoebae having a relatively constant size and location in each species.
When the case was referred to the parasitology laboratory (Infectious Diseases Department, Pavia University Hospital), a definitive diagnosis of PAM was made on the basis of morphology of amebic trophozoites, which exhibited a conspicuous karyosome, a vacuolated cytoplasm, and a mean diameter of 10 [micro]m to 12 gm.