American Journal Of Biomedical Science & Pharmaceutical Innovation
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VOLUME
Vol.05 Issue04 2025
PAGE NO.
19-20
10.37547/ajbspi/Volume05Issue04-04
Sexual Chromatin: Structure, Functions and Significance
in Medical Practice
Qurbonov A. Q.
Department of Histology and Medical Biology, Tashkent Medical Academy, Uzbekistan
Yuldasheva Z.Z.
Department of Histology and Medical Biology, Tashkent Medical Academy, Uzbekistan
Received:
17 February 2025;
Accepted:
15 March 2025;
Published:
16 April 2025
Abstract:
The concept of sex chromatin plays an important role in genetics, cytology and medical practice. Sex
chromatin is a condensed inactive X chromosome in the nucleus of somatic cells in female mammals. This
phenomenon is explained by a dosage compensation mechanism that ensures equal amounts of X-sex
chromosome gene products in males and females. Sex chromatin is an important object of cytogenetic studies,
allowing the diagnosis of disturbances in the number of X-sex chromosomes and the differential diagnosis of
hereditary chromosomal diseases.
Keywords:
Sex chromatin, Barr bodies, X-sex chromosome, genotype, trisomy, Klinefelter syndrome, Turner
syndrome, amniotic fluid.
Introduction:
Sexual chromatin was first described in
1949 by Canadian scientist Murray Barr and his
colleague E. Bertram while studying the cells of the
nervous tissue of cats. They found a dense colored div
near the nuclear membrane, which was present only in
females. Later, it was found that this formation
corresponds to the inactivated X-sex chromosome.
Further studies confirmed the presence of Barr bodies
in other mammals and explained the mechanism of X-
sexual inactivation.
Sex chromatin, a dense, staining div found in the non-
dividing nuclei of cells in heterogeneous (having X and
Y sex chromosomes) animals and humans. Sexual
chromatin is divided into X-chromatin, or Barr's div,
and Y-chromatin (discovered in 1970 by Swedish
scientists T. Kaspersky and L. Tsekh). X-chromatin is a
div that is intensely stained with basic dyes (0.7
—
1.2
microns), more often adjacent to the nuclear envelope
and having a triangular semilunar or rounded shape. Y-
chromatin is much smaller in size and is detected when
the nucleus is stained with fluorochromes (akrikhin,
akrikhiniprit) and examined in ultraviolet light. In
female individuals (type XX), one of the X chromosomes
is inactive, which is manifested in its stronger
spiralization and densification. In the interphase
nucleus, this spiralized X chromosome is visible as X-
chromatin. Y-chromatin in humans and some primates
has a large heterochromatin region that produces
intense fluorescence. Thus, a technically simple study
of the interphase nucleus makes it possible to judge the
state of the sex chromosome system. X-chromatin is
more or less often found in women in the nuclei of cells
of all tissues (for example, in the epithelial cells of the
oral mucosa in 15-60% of the nuclei). The number of
nuclei with X-chromatin depends on the intensity of cell
reproduction in a given tissue and on the hormonal
state of the div. A change in the amount of sex
chromatin indicates a change in the number of sex
chromosomes, which is detected by the cytogenetic
method of human genetics.
The nature and formation of sex chromatin was first
explained by the English geneticist Mary Lyon in 1961.
When comparing the female (XX) and male (XY) sex
chromosomes, it was found that the genes in the X
chromosome can show all the signs on their own
without forming XX. For example, men (XY) have one X
chromosome, but it alone carries all the information.
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
Based on this, Lyon explained the formation of sex
chromatin. In women, one of the X-sex chromosomes
is inactive, it is formed at the stage of the interphase of
DNA division from an inactive strongly twisted and
spiralized chromosome, and it also forms a small div
clearly visible under the microscope. And the second X
chromosome is active, it carries genes that manifest
their functions, and the DNA is in an unspiralized state,
in the form of a thin long strand. For this reason, this
chromosome is not visible under a microscope.
The transition to the inactive state of one of the X
chromosomes in the female div is observed randomly
in the early embryonic period. However, the property
of DNA division in an inactive chromosome remains. In
the female div, one X chromosome is derived from
the father, the other from the mother. The
manifestation of symptoms depends on the transition
of one of the sex chromosomes to an inactive state. If
the chromosome received from the mother contains
dominant genes, but becomes inactive, then the
chromosome received from the father with recessive
features will manifest itself.
Since the inactivation of the X-sex chromosome occurs
randomly, women are mosaics of X-linked genes. This
leads to unique biological features. The coat color of
tortoiseshell cats is a good example of mosaic gene
expression. Mosaicism in the case of X-linked diseases
–
some cells may be healthy, while others may be
mutant, which mitigates the manifestations of diseases
such as hemophilia or Duchenne syndrome in humans.
A method for determining sex chromatin in medicine:
1. In the diagnosis of hereditary chromosomal diseases.
If no sex chromatin is detected in a woman's div, it is
revealed that she has one X-sex chromosome. This
genotype is observed in women suffering from
Shereshevsky-Turner disease. If there is one extra sex
chromatin, then the woman has an excess of the X
chromosome, i.e. a trisomy in the genotype. Usually,
men do not have sex chromatin, but people suffering
from Klinefelter's disease have excess sex chromatin.
2. In obstetric and gynecological practice, this method
is used to determine the sex of the fetus, where the test
material is amniotic fluid, into which fetal cellular
substances are secreted. Also, this research method
makes it possible to find out the probability of having a
hemophiliac if the family already has a son suffering
from hemophilia. If there is sexual chromatin in the
amniotic fluid, the sex of the fetus is a girl and she will
be born healthy. If sexual chromatin is not observed,
then the sex of the child is a boy and the probability of
hemophilia is 50%.
3. In pediatric practice, in some cases children are born
bisexual, i.e. hermaphrodites. According to the
presence or absence of sexual chromatin, the child's
proper sex is determined and various measures are
taken to form a natural medical gender.
4. In transplantation.
5. In the forensic medical examination. Using the
method of determining sex chromatin, it is possible to
determine the sex of a person.
CONCLUSION
Sex chromatin is an important object of study in the
field of human genetics and medicine, since the
method of determining sex chromatin allows us to
obtain valuable data on sex chromosomes and their
behavior in cells. The use of sex chromatin research
methods is widely used in the diagnosis of various
human chromosomal diseases, as well as in various
areas of medical practice.
REFERENCES
К.Н. Нишанбаев, П. Р. Алимходжаева, Д. Х. Хамидов,
«Медицинская биология и генетика», 2008г.
,
Государственное
Научное
издательство
«Узбекистон миллий энциклопедияси» Ташкент;
К.Н.
Нишанбаев,
П.Р.
Алимходжаева,
Л.И.
Шамансурова,
«Медицинская
биология
и
генетика»,
2009г.,
Государственное
Научное
издательство
«Узбекистон
миллий
энциклопедияси» Ташкент;
Гинтер, Е. К., «Медицинская генетика», 2009г., СПб.:
Издательство СПбГУ;
Жуков, Б. Н., & Иванова, Л. Н., «Основы
цитогенетики человека», 2010г., М.: Наука;
В. Н. Ярыгин, «Биология» учебник, под редакцией
академика РАМН профессора, 2018г, том 1,2;
издательство ГЭОТАР –
Медиа, Москва;
Халиков П.Х., Курбанов А.К., Даминов А.О.,
«Медицинская биология и генетика», 2023г.
