Barr bodies

A barr body is an inactive X chromosome in female cells or the inactive Z in a male. Lyonization is the process where the chromosome is inactivated in species.

In men and women with more than one X chromosome, the number of Barr bodies visible at interphase is always one less than the total number of X chromosomes.

For example, a man with Klinefelters syndrome, with 47 chromosomes, XXY karyotype have two Barr bodies, whereas an female with Turners syndrome, with 45 chromosomes, XO karyotype does not have any Barr bodies.