Mass of condensed sex chromatin in the nuclei of normal female somatic cells due to inactive X chromosome. Barr and Ewart George Bertram (1923–)showed that it is possible to determine the genetic sex of an individual according as to whether there is a chromatin mass present on the inner surface of the nuclear membrane of cells with resting or intermitent nuclei (sex chromatin).
According to the Lyon hypothesis, one of the two X xhromosomes in each somatic cell of the female is genetically inactivated. The Barr body represents the inactivated X chromosome. X inactivation occurs around the 16th day of embryonic development. The term Barr body was introduced by Mary Lyon.
- M. L. Barr and E. G. Bertram:
A morphological distinction between neurones of the male and female, and the behaviour of the nucleolar satellite during accelerated nucleoprotein synthesis.
Nature, London,1949, 163: 676-677.
- Keith Leon Moore (1925–), M. A. Graham and M. L. Barr:
The detection of chromosomal sex in hermaphrodites from a skin biopsy.
Surgery, Gynecology and Obstetrics, Chicago, 1953, 96: 641-648.
Sex chromatin demonstrated in humans.
- M. L. Barr:
Testicular dysgenesis affecting the seminoferous tubules principally with chromatinpositive nuclei.
The Lancet, London, 1956, 1: 853-856.
- M. L. Barr:
Sex chromatine and phenotype in man. Disagreement between nuclear sex and phenotype raises questions about the cause of sex anomalies.
Science, Washington, 1959, 30: 679-735.
- B. H. Barr:
An unusual sex chromatin pattern in three mentally deficient subjects.
Journal of Mental Deficiency Research, Oxford, 1963, 3: 78-87.