Barr body

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The small, dark-staining mass of inactive X chromosome within the nucleus of non-dividing cell.


Barr bodies are previously used as the basis for sex determination especially during the Olympics (see Barr test).

Word origin: named after its discoverer Murray Llewellyn Barr, a Canadian anatomist who first identified the particle in the nucleus of neurons of female cats.

Synonym: sex chromatin

See also: Barr test