Before revision: barr body, magnif.1000x, in nucleus of female human mouth-epithelial-cell, cresyl violet stain|alt= A Barr body (named after discoverer Murray Barr) is an inactive X chromosome in a cell with more than one X chromosome, rendered inactive in a process called lyonization, in species with XY sex-determination (including humans).
After revision: or X-chromatinbarr body, magnif.1000x, in nucleus of female human mouth-epithelial-cell, cresyl violet stain|alt= A Barr body (named after discoverer Murray Barr) is an inactive X chromosome in a cell with more than one X chromosome, rendered inactive in a process called lyonization, in species with XY sex-determination (including humans).