Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in cells other than egg cells. This phenomenon is called X-inactivation or lyonization. X-inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell.

What causes Lyonization?

Lyonization is commonly known as X-inactivation. In mammals, males receive one copy of the X chromosome while females receive two copies. To prevent female cells from having twice as many gene products from the X chromosomes as males, one copy of the X chromosome in each female cell is inactivated.

How do you get Barr bodies?

The barr body is calculated as one less than the total number of X chromosomes present. If we calculate the barr body in the female which has XX chromosomes, the barr body will be one. If we calculate the barr 's body in males, males have XY chromosomes so the barr body will be zero in males.