sex chromatin

Barr body   (bär)    n.  The condensed, inactive X-chromosome found in the nuclei of somatic cells of most female mammals. Also called sex chromatin. [After Murray Llewellyn Barr (1908-1995), Canadian anatomist.]

Main Entry: Barr body
Pronunciation: 'bär-
Function: noun
: a densely staining inactivated condensed X chromosome that is present in each somatic cellof most female mammals and is used as a test of genetic femaleness (as in a fetus or an athlete) called also sex chromatin
Barr, Murray Llewellyn (1908–1995)Canadian anatomist. A professor of microanatomy, Barr specialized in cytological research, especially as it applies to genetically determined anomalies of sex determination and development, cancer, andmental disease. His most notable work dealt with sex chromatin, now known as the Barr body. In 1949 he noted that females had in the nuclei of their nerve cells a mass of chromatin that males did not.Further study revealed that this sex difference in the nuclei of resting cells is found in most mammals.

Barr body (bär)
n.
The condensed, inactive, single X-chromosome found in the nuclei of somatic cells of most female mammals and whose presence is the basis of sex determination tests that are performed, for example, on athletes. Also called sex chromatin.