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单词 sex chromatin
释义

sex chromatin


sex chromatin

n. See Barr body.

Barr′ bod`y

(bɑr)
n. an inactive Xchromosome present in the nuclear membrane of female somatic cells, used for verifying the sex of an individual. [1960–65; after Murray Latin. Barr (born 1908), Canadian physician]
Thesaurus
Noun1.sex chromatin - chromatin found only in female cells; "the presence or absence of sex chromatin in cells obtained by amniocentesis makes it possible to determine the sex of a fetus"chromatin, chromatin granule - the readily stainable substance of a cell nucleus consisting of DNA and RNA and various proteins; during mitotic division it condenses into chromosomes

Sex Chromatin


sex chromatin

[′seks ′krō·mə·tən] (cell and molecular biology) Barr body

Sex Chromatin

 

a solid stained body found in the nondi-viding interphasic nuclei of cells in heterogamous (having X and Y sex chromosomes) animals and in man. There are two types of sex chromatin: the X chromatin, or Barr body, discovered in 1949 by the British researchers M. Barr and E. G. Bertram, and the Y chromatin, discovered in 1970 by the Swedish scientists T. Caspersson and L. Zech.

The chromatin is a body that is intensively stained by basic dyes (0.7–1.2 micrometers) and usually found adjacent to the nuclear membrane. It has a triangular, crescent, or round shape. The Y chromatin is much smaller and is visible when the nucleus is stained by fluorochromes, such as quinacrine hydrochloride or quinacrine yperite, and examined under ultraviolet light. In individuals of the female sex (XX type), one of the X chromosomes is inactive. This is shown by its greater spiralization and consolidation. The spiraled X chromosome is also visible in an interphasic nucleus in the form of X chromatin. The Y chromosome in man and some primates has a large heterochromatin area which is strongly fluorescent.

A technically simple examination of an interphasic nucleus reveals the condition of the system of sex chromosomes. The X chromatin is found more or less frequently in women in the nuclei of all tissue cells, for example, in 15–60 percent of the nuclei in the epithelial cells of the oral mucous membrane. The number of nuclei with X chromatin depends on the rate of cell reproduction in a given tissue and on the hormonal state of the organism. A change in the quantity of sex chromatin shows that there has been a change in the number of sex chromosomes. This can be ascertained in more detail by analyzing the karyotype. Sex chromatin is widely used to determine the sex of an unborn child. This is necessary in those cases where there is a possibility of inheriting sex-linked diseases.

REFERENCES

Zakharov, A. F. “Novye metody analiza khromosom cheloveka.” In Itogi nauki i tekhnika: Seriia “Genetika cheloveka,” vol. 1. Moscow, 1973.
“Fluorescent Staining of Heteropycnotic Chromosome Regions in Human Interphase Nuclei.” Experimental Cell Research, 1970, vol. 61, nos. 2–3.
The Sex Chromatin. Edited by K. L. Moore. Philadelphia-London, 1966.

K. N. GRINBERG

sex chromatin


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

sex chromatin

n. 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.

sex chromatin

see BARR BODY.

Barr,

Murray Liewellyn, Canadian microanatomist, 1908–. Barr body - Synonym(s): Barr chromatin bodyBarr 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
LegalSeeSex

sex chromatin


Related to sex chromatin: Barr body
  • noun

Words related to sex chromatin

noun chromatin found only in female cells

Related Words

  • chromatin
  • chromatin granule
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