Sex chromatin

Often in gynecology and pediatric andrology, there is a need to conduct a genetic examination of the patient. This method allows you to more reliably identify the causes of the ailment, choose the appropriate course of treatment and determine the predictions in the development of the disease.

Sex chromatin is an important indicator of normal sexual development at the cellular level. Its diagnosis is necessary in cases when it comes to anomalies in the structure of the external genitalia. The study is also conducted in the detection of diseases caused by chromosomal pathologies and in the presence of signs of impaired sexual development. The reason for this may be the lack of menstruation in girls and underdevelopment of the ovaries or a decrease in their function in boys.

Sex chromatin was first discovered by scientist J. Bar in 1949. While studying the nerve cells of a cat, he noticed a chromatin formation on the periphery of the nucleus. Subsequently, this important feature of female somatic cells was detected in most of the representatives of the order of mammals. In the male cells such bodies were not found. Taurus Barra is a component of all somatic cells of women. And in some cases it has peculiar appendages ("drumsticks"). Somatic cells are integral parts of the human body. These include all the cells of the body, except gametes. This discovery made it possible to broaden the concept of methods for determining sex in humans and mammals.

The presence of Barra's bodies in the female body is explained by the presence of two X chromosomes in somatic cells. And only one of them has activity. That's why in the female cells there is always a body of Barra. This theory further allowed to detect anomalies in the development of the organism. So, a cell with three chromosomes will have two bodies, with four - three, etc. Diagnosis of abnormal cell development can be used for both men and women. Since 1953, this discovery has been actively used to determine the exact number of X chromosomes in people with developmental disorders.

The sexual chromatin, or Barra's body, looks like a dark mass of round, triangular or rodlike shape, which is located near the inner surface of the core membrane. This is an inactive X chromosome, which in its diameter does not exceed 1 micron. The detection of Barr bodies in 10-12% of the cells examined indicates a positive sexual chromatin. The material of the study is usually the epithelium of the mucous membrane of the cheek (inner surface), the vagina, the hair follicles and amniotic fluid. If the indicator did not exceed 5%, this indicates a negative sex chromatin.

Sex chromatin causes differences in interphase nuclei in men and women. It is associated with the features of the functioning of reproductive systems and their structure. Taurus Barra is of two kinds: Y and X. The first variant is a structural component of the Y-chromosome and is found mainly in men. For these purposes, use fluorochrome with the use of ultraviolet light. X-chromatin (Barra's body) is an inactivated X chromosome. Its deactivation takes place during the first weeks of intrauterine development and remains for a long time during mitotic division.

It should be noted that sexual chromatin is a dynamic structure. It can vary depending on the general condition of the body and the metabolism of cells. It is for this reason that the examination is not recommended during the use of hormonal drugs, in the first days after birth, after taking antibiotics and other medicines.

Today, according to the presence of sexual chromatin, physicians determine the genetic sex of the unborn child, diagnose various clinical forms of dysgenesis of gonads and hermaphroditism. Analyzes for the detection of this component are widely used in forensic medicine.