Barr body

In those species (including humans) in which sex is determined by the presence of the Y or W chromosome rather than the diploidy of the X or Z, a Barr body is the inactive X chromosome in a female cell, or the inactive Z in a male (Lyon, 2003), rendered inactive in a process called Lyonization. The Lyon hypothesis states that in cells with multiple X chromosomes, all but one is inactivated during mammalian embryogenesis (Lyon, 1961). This happens early in embryonic development at random in mammals, (Brown, 1997) except in marsupials and in some extra-embryonic tissues of some placental mammals, in which the father's X chromosome is always deactivated (Lee, 2003). Barr bodies are named after their discoverer, Murray Barr (Barr & Bertram, 1949).
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A microscopic feature of female cells due to the presence of two X chromosomes in the female. One of these X chromosomes is inactive and is crumpled up to form the Barr body.

Also called sex-chromatin body which represents the inactivated X chromosome in the nucleus of somatic mammalian cells. Normally only seen in female cells and not in male cells.

B: (Biologi) tubuh Barr
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