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 establish the causes of the ailment, select the necessary course of treatment and determine the prognosis 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 those cases when it comes to abnormalities in the structure of the external genitalia. The study is also carried out in identifying 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 the scientist J. Bar in 1949. Conducting a study of cat nerve cells , 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 mammalian order. No such bodies were found in male cells. Taurus Barra is a component of all somatic cells in women. And in some cases it has peculiar appendages (“drumsticks”). Somatic cells are integral components of the human body. These include all cells of the body, except gametes. This discovery allowed us to expand our understanding of methods for determining sex in humans and mammals.
The presence of Barr bodies in the female body is explained by the presence of two X chromosomes in somatic cells. Moreover, only one of them has activity. That is why in female cells there is always a body of Barra. This theory subsequently made it possible to identify 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.
Sex chromatin, or Barr's body, in appearance resembles a dark mass of round, triangular or rod-shaped, which is located near the inner surface of the core membrane. This is an inactive X chromosome, which in diameter does not exceed 1 micron. Detection of Barr bodies in 10-12% of the studied cells indicates a positive sex chromatin. The study material is usually the epithelium of the mucous membrane of the cheek (inner surface), the vagina, hair follicles, and amniotic fluid. If the indicator does 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 the reproductive systems and their structure. There are two types of Barra body: Y and X. The first option is a structural component of the Y chromosome and is detected mainly in men. For this purpose, use fluorochrome using ultraviolet light. X-chromatin (Barr body) is an inactivated X chromosome. Its deactivation occurs in the first weeks of fetal development and persists for a long time during mitotic division.
It should be noted that sex chromatin is a dynamic structure. It can vary depending on the general condition of the body and cell metabolism. For this reason, it is not recommended to conduct an examination during the use of hormonal drugs, in the first days after birth, after taking antibiotics and other drugs.
Today, according to the presence of sex chromatin, doctors determine the genetic gender of the unborn child, diagnose a variety of clinical forms of gonadal dysgenesis and hermaphroditism. Tests for the detection of this component are widely used in forensic practice.