question: What is the Barr body?
answer: The Barr body is the inactive X chromosome in a female somatic cell. It is readily identified as plano-convex structure of 2-3 micron in diameter on the periphery of the nuclear membrane.   One of the X-chromosomes by a random inactivation process condenses to form X-chromatin (Barr body) in early embryonic life. Once this occurs, it is final and fixed for that cell and all its descendants (1,2).  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.   The Barr body has long been recognized as the cytological manifestation of the inactive X chromosome (Xi) in interphase nuclei. Despite being known for over 50 years, relatively few components of the Barr body have been identified.  