Sex chromatin

Often in gynecology and pediatric andrology, the need arises to carry out a genetic examination of the patient. This method allows you to more reliably determine the causes of the disease, to choose the necessary treatment and determine the prognoses in the development of the disease.

Sex chromatin – an important indicator of normal sexual development at the cellular level. His diagnosis is necessary in cases when we are talking about anomalies in the structure of external genitalia. The study is being conducted to help identify diseases caused by chromosomal abnormalities and the presence of signs of violation of sexual development. The reason for this can be absence of menstruation in girls, and underdevelopment of the ovaries or decrease their function in boys.

Sex chromatin was first discovered by the scientist John. Bar in 1949. Conducting research of nerve cells of a cat, he noticed on the periphery of the nucleus chromatin formation. Subsequently, this important feature of female somatic cells was revealed in most representatives of the order of mammals. In the cells of the male such corpuscles were not detected. Barr body is a component of all somatic cells of women. And in some cases it has a kind of appendages (“sticks”). Somatic cells – is an integral component of the human body. These include all cells of the body except the gametes. This discovery helped to expand the understanding of methods of sex determination in humans and mammals.

The Presence in the female body Barr body is due to the presence of somatic cells of two X-chromosomes. Moreover, activity is only one of them. That is why in women's cells always have a Barr body. This theory is further enabled to detect anomalies in development of the organism. So, a cell with three chromosomes will have two Taurus, four-three, etc. Diagnosis of abnormal development of cells can be used for both men and women. Since 1953, the discovery was actively used to determine the exact number of X chromosomes in people with disabilities.

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Sex chromatin, or Barr body, looks like a dark mass of rounded, triangular or rod-shaped, which is located near the inner membrane surface of the nucleus. This is the inactive X chromosome, which in its diameter does not exceed 1 MK. Detection of Barr body in 10-12% of the studied cells indicates a positive sexual chromatin. The research usually is the epithelium of the buccal mucosa (inner surface), the vagina, hair follicles, and amniotic fluid. If the indicator did not exceed 5 %, this indicates a negative sex chromatin.

Determines the Sex chromatin of interphase nuclei of the differences in men and women. It is associated with the peculiarities of the reproductive system and their structure. Barr body 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 the fluorochrome with the use of ultraviolet light. X-chromatin (Barr body) – inactivated X chromosome. Its deactivation occurs in the first weeks of fetal development and remains in mitosis for a long time.

It Should be noted that sex chromatin-this structure is dynamic. It can vary depending on the General condition of the organism and the cell metabolism. For this reason, routine screening is not recommended during the use of hormonal drugs, in the first days after birth, after taking antibiotics and other drugs.

Today, the presence of sexual chromatin doctors determine the genetic sex of a child diagnosed with different clinical forms of gonadal dysgenesis and hermaphroditism. Tests for detection of this component are widely used in forensic practice.