A dense clump of chromatin found only in female cells, which can be used to identify the sex of a baby before birth [Described 1949. After Murray Llewellyn Barr (1908-95), head of the Department of Anatomy at the University of Western Ontario, Canada.]
Mass of chromosomal material normally seen within female body cells. Though females have two X- chromosomes, one is normally inactivated during development. The Barr body represents the inactivated X-chromosome.
Sex chromatin mass seen within the nuclei of normal female somatic cells. According to the Lyon hypothesis, one of the two X chromosomes in each somatic cell of the female is genetically inactivated. The Barr body represents the inactivated X chromosome.