BARR BODY Meaning and
Definition
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A barr body, also known as a Barr chromatin body or sex chromatin body, refers to a dense, inactive X chromosome that is visible within the nuclei of female mammalian cells. It is named after Murray Barr, the Canadian-Australian physician who first described it in 1949. The presence of a barr body is a result of X chromosome inactivation, a process that occurs in females to balance gene expression between the sexes.
In female mammals, both X chromosomes contain a similar set of genes, but only one of them is active in each cell. To achieve dosage compensation, one of the two X chromosomes is randomly inactivated during early development, resulting in the formation of a condensed, sex chromatin body - the barr body.
Under a light microscope, a barr body appears as a small, dark-staining clump located at the periphery of the nucleus. It consists of tightly coiled DNA, along with various proteins, which help facilitate transcriptional silencing of the inactive X chromosome. The formation of a barr body ensures that males and females have an equal expression of X-linked genes, despite females having two X chromosomes.
The presence of a barr body has been widely used in cytogenetics and histopathology to determine the sex of an individual, particularly if there are chromosomal abnormalities or intersex conditions present. However, it is important to note that the formation of a barr body is not exclusive to females, as certain individuals with chromosomal disorders or anomalies may also possess barr bodies.
Common Misspellings for BARR BODY
- varr body
- narr body
- harr body
- garr body
- bzrr body
- bsrr body
- bwrr body
- bqrr body
- baer body
- badr body
- bafr body
- batr body
- ba5r body
- ba4r body
- bare body
- bard body
- barf body
- bart body
- bar5 body
- bar4 body
Etymology of BARR BODY
The term "barr body" is named after Murray Barr, a Canadian anatomist and geneticist who first observed this structure in the nuclei of cells. In 1949, Murray Barr and his colleague Ewart Bertram discovered a darkly staining, densely compacted structure inside the nuclei of female mammalian cells. They found that this structure was absent in male cells and concluded that it was related to an X chromosome phenomenon.
The Barr body is a condensed, inactive X chromosome that has been randomly chosen to be silenced in female cells through a process called X chromosome inactivation. This inactivation mechanism compensates for the double dose of X chromosome genes in females compared to males.
Thus, the term "barr body" was coined to honor Murray Barr's contribution to the understanding of X chromosome inactivation in female cells.
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