An
interphase
epithelial cell from a human
female
shows a dark-staining
Barr body
in the nucleus; representing an
inactivated
X
chromosome.
A comparable cheek epithelial cell from a
male
does not show a
Barr body
.
Thus,
dosage compensation
prevents excessive expression of X-linked genes in mammals.
An interphase epithelial cell from a human female shows a dark-staining Barr body
in the nucleus; representing an inactivated X chromosome.