Barr body is an inactivated X chromosome in the normal female somatic cell. 
Inactivation of these chromosomes is known as Lyonization. Lyonization has both 
genetic and clinical significance. Barr body can be easily identified with 
ordinary stains. It also helps in identifying the sex of an individual when used 
judiciously. A review is made on the lyonization of Barr body and its utility in 
sex determination.