Search results
Results From The WOW.Com Content Network
A Barr body (named after discoverer Murray Barr) [1] or X-chromatin is an inactive X chromosome. In species with XY sex-determination (including humans), females typically have two X chromosomes, [ 2 ] and one is rendered inactive in a process called lyonization .
The Barr body is indicated by the arrow, it identifies the inactive X (Xi). ... Since males only have one copy of the X chromosome, all expressed X-chromosomal genes ...
Ohno's studies of Barr bodies in female mammals with multiple X chromosomes revealed that such females used Barr bodies to inactivate all but one of their X chromosomes. Thus, Ohno described the "n-1" rule to predict the number of Barr bodies in a female with n number of X chromosomes in her karyotype. [6]
The Barr body is indicated by the arrow. They are only present in cells with XX chromosomes. This was the evidence searched for in Barr body tests of samples from female athlete's inner cheeks. From 1958 to 1992, all female athletes underwent mandatory sex verification tests before taking part in any IAAF or IOC event.
The cells of those born male contain an X chromosome and a Y chromosome that make a pair and give instructions on which genes should be expressed in the body, the researchers said. As males age ...
Nuclear sexing can be done by identifying Barr body, a drumstick like appendage located in the rim of the nucleus in somatic cells. Barr body is the inactive X chromosome which lies condensed in the nucleus of somatic cells. A typical human (or other XY-based organism) female has only one Barr body per somatic cell, while a typical human male ...
This phenomenon is called X-inactivation or Lyonization, and creates a Barr body. If X-inactivation in the somatic cell meant a complete de-functionalizing of one of the X-chromosomes, it would ensure that females, like males, had only one functional copy of the X chromosome in each somatic cell. This was previously assumed to be the case.
In the past, the observation of the Barr body was common practice, as well. [47] To investigate the presence of a possible mosaicism, analysis of the karyotype using cells from the oral mucosa is performed. Physical characteristics of a Klinefelter syndrome can be tall stature, low body hair, and occasionally an enlargement of the breast.