Murray Barr

Murray Llewellyn Barr was an anatomical researcher and medical educator at the University of Western Ontario. In 1949, while studying nerve fatigue in cats alongside graduate student Ewart Bertram, Barr noticed a dark condensed chromatin mass in the nuclei of female nerve cells that was absent in male cells.

This structure, named the "Barr body," was identified as the inactive X chromosome in female mammalian cells. The discovery founded modern diagnostic cytogenetics, enabling simple chromosomal testing for conditions such as Turner syndrome, Klinefelter syndrome, and intersex variations, and earning Barr numerous international honors including the Gairdner Foundation Award.