sex chromatin

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chromatin

 [kro´mah-tin]
the substance of the chromosomes, composed of DNA and basic proteins (histones), the material in the nucleus that stains with basic dyes.
sex chromatin the persistent mass of the material of the inactivated X chromosome in cells of normal females; called also Barr body.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

sex chro·ma·tin

a small condensed mass of the inactivated X-chromosome usually located just inside the nuclear membrane of the interphase nucleus; the number of sex chromatin bodies per nucleus is one less than the number of X-chromosomes; normal males and females with Turner syndrome (XO) have none (sex chromatin negative), normal females and males with Klinefelter syndrome (XXY) have one, and XXX-females have two. For technical reasons only about half the cells in a preparation show typical masses.
See also: Lyon hypothesis.
Synonym(s): Barr chromatin body
Farlex Partner Medical Dictionary © Farlex 2012

sex chromatin

n.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

Barr body

A condensed clump of chromatin that corresponds to an inactivated X chromosome, which is located next to the nuclear membrane, and best seen in somatic cells in interphase. The number of BBs per cell is 1 less than the number of X chromosomes, thus normal XX women cells will have one BB, as do men with 47 XXY (Klinefelter syndrome). Normal XY males have none, nor do 45 XO (Turner syndrome) females.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

sex chro·ma·tin

(seks krō'mă-tin)
A small, condensed mass of the inactivated X-chromosome usually located just inside the nuclear membrane of the interphase nucleus; the number of sex chromatin bodies per nucleus is one less than the number of X-chromosomes; hence, normal males have none and normal females have one. For technical reasons, only about half the cells in a preparation show typical masses.
See also: Lyon hypothesis
Synonym(s): Barr chromatin body.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

sex chromatin

see BARR BODY.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

Barr,

Murray Liewellyn, Canadian microanatomist, 1908–.
Barr body - Synonym(s): Barr chromatin body
Barr chromatin body - a small condensed mass of the inactivated X-chromosome usually located just inside the nuclear membrane of the interphase nucleus. Synonym(s): Barr body; sex chromatin
Medical Eponyms © Farlex 2012