Barr body

A Barr body is an inactivated, condensed form of one of the two X chromosomes found in female cells. Since females have two X chromosomes, one is randomly turned off during early development to balance gene expression with males, who have only one X. This inactivation results in the Barr body, which appears as a dense, dark spot in the cell nucleus under a microscope. The process ensures that females do not produce double the amount of X-linked genes compared to males, maintaining genetic balance between sexes.