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.

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

See Barr body.

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.

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

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References in periodicals archive

He found that sex chromatin can be studied by this method.

Picture.2: Showing no sex chromatin in the nucleus of buccal mucosal epithelial cell belongs to male individual.

In all 50 females slides the sex chromatin was positive and it varied from 20-50% in the age group of 12 years to above 60 years.

Evaluation of Barr bodies or Screening of sex chromatin: In this present study the criteria of the Hse et al 1967, has been employed for the nuclei examined for sex chromatin choosing the first.

DISCUSSION: Sex can determine by studying the presence of sex chromatin in various tissue of the body, i.e.

Unfortunately tissues which are suitable for clinical studies from the oral mucosa have much lower frequencies(36-76%) when compared with the sex chromatin frequencies obtained from female foetal membrane was 96% and 85-95% from the neurons.

In the present study it was observed that the chromatin in the frequency of 40.14% in all female cells with average sex chromatin varied from 20-52%, while none of the male cases showed sex chromatin.

However daily buccal smear from 42 female babies showed at the 3rd day the sex chromatin frequency rises and was comparable to that found in older females.

A study of sex cheromatin form buccal smear