Final answer:
X inactivation in females involves the condensation of one X chromosome into a Barr body, which balances gene expression between males and females by ensuring only one active X chromosome is present in each cell.
Step-by-step explanation:
In mammals, to prevent a double dose of X-chromosome gene products from causing a biochemical imbalance in females, a process known as X inactivation occurs. During embryonic development, one of the two X chromosomes in each female cell condenses into a structure called a Barr body, rendering the genes on the inactive X chromosome unexpressed. This random inactivation ensures that females, like males, end up with a single functional set of X chromosome genes, thereby maintaining genetic balance. For instance, in "tortoiseshell" cats, this phenomenon can be seen visually as patches of different colored fur, which reflect the random inactivation pattern of X chromosomes in cells responsible for coat color.