BARR BODIES Meaning and
Definition
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Barr bodies refer to specialized structures that can be found within the cell nuclei of female mammalian cells. They are a result of inactivation of one of the two X chromosomes (X-inactivation) in females. This process ensures dosage compensation between males and females, as females possess two X chromosomes and males have one X and one Y chromosome.
When X-inactivation occurs, one of the X chromosomes condenses and forms a compact, dense, and transcriptionally inactive structure known as a Barr body. The Barr body is characterized by tightly coiled chromatin and is typically seen as a small, dark spot within the nucleus of a female cell. The inactivated X chromosome within the Barr body becomes heterochromatic and is largely devoid of gene expression.
Barr bodies were first discovered by Murray Barr and Ewart Bertram in the 1940s using microscopy techniques. Their presence can serve as a cytogenetic marker for sex determination in certain clinical scenarios, as the presence of more than one Barr body can indicate chromosomal abnormalities such as Turner syndrome or Klinefelter syndrome.
Overall, Barr bodies are a visual manifestation of X-inactivation in female cells and play a crucial role in equalizing gene expression between males and females.
Common Misspellings for BARR BODIES
Etymology of BARR BODIES
The term "Barr bodies" is named after its discoverer, Murray Barr, a Canadian physician and medical researcher. In 1949, Barr and his colleague Ewart Bertram observed a densely stained structure within the nuclei of female mammalian cells, which is absent in male cells. They referred to this structure as a "Barr body" in honor of Murray Barr's contribution to its discovery. The term has since become widely used in biology and genetics to describe the condensed, inactive X chromosome found in female somatic cells.
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