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Determination of X- and Y-chromatin
Last reviewed: 23.04.2024
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The definition of X- and Y-chromatin is often called the method of express diagnostics of sex. Explore the cells of the mucosa of the mouth, vaginal epithelium or hair bulb. In the nuclei of cells of women in a diploid set, there are two chromosomes X, one of which is completely inactivated (spiralized, tightly packed) already in the early stages of embryonic development and is visible as a heterochromatin block attached to the core shell. The inactivated chromosome X is called the sex chromatin or Barr's body. To detect sex X-chromatin (Barr's body) in the nuclei of the cells, smears are stained with acetarine and the preparations are examined using a conventional light microscope. Normally, women have a single lump of X chromatin, and men do not.
To identify male Y-sexual chromatin (F-body), smears are stained with acrichine and viewed with a luminescent microscope. Y-chromatin is detected as a strongly luminous point, in magnitude and intensity of luminescence different from the rest of the chromocenter. It is found in the nuclei of cells of the male body.
The absence of the Barra body in women indicates a chromosomal disease - the Shereshevsky-Turner syndrome (karyotype 45, X0). The presence of the male Barr in the male testifies to the Kleinfelter syndrome (karyotype 47, XXY).
The determination of X- and Y-chromatin is a screening method, the final diagnosis of chromosomal disease is posited only after the study of a karyotype.
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