https://doi.org/10.1351/goldbook.11210
Condensed mass of one inactivated X chromosome seen inside the nuclear membrane of an interphase cell.
Note: The Barr body is not seen in normal male cells (XY), but one body may be seen in normal female cells (XX). In chromosomal abnormalities, the number seen is one less than the number of X chromosomes.
See also: Lyon hypothesis