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 VOLUME Vol.05 Issue04 2025 

PAGE NO. 19-20 

DOI 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 body 
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 body 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 body, 
and Y-chromatin (discovered in 1970 by Swedish 
scientists T. Kaspersky and L. Tsekh). X-chromatin is a 
body 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 body. 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 20 https://theusajournals.com/index.php/ajast 

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 body 
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 body is observed randomly 
in the early embryonic period. However, the property 
of DNA division in an inactive chromosome remains. In 
the female body, 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 body, 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. 

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