Science / Genetics / X-Inactivation: The repression of one of the two x-chromosomes in the somatic cells of females as a method of dosage compensation: at an early embryonic stage in the normal female, one of the two x-chromosomes undergoes inactivation, apparently at random, from this point on all descendent cells will have the same x-chromosome inactivated as the cell from which they arose, thus a female is a mosaic composed of two types of cells, one which expresses only the paternal x-chromosome, and another which expresses only the maternal x-chromosome.
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