Rv. Jamieson et al., X-CHROMOSOME INACTIVATION DURING THE DEVELOPMENT OF THE MALE UROGENITAL RIDGE OF THE MOUSE, The International journal of developmental biology, 41(1), 1997, pp. 49-55
In the mouse, the activity of Sry (sex-determining gene on the Y chrom
osome) initiates the transformation of the indifferent gonad into a te
stis. In humans, a partial Xp21 duplication leads to the development o
f ovaries instead of testes in XY individuals. This observation indica
tes that sex determination might also be influenced by a gene-dosage c
ompensation mechanism, in addition to a dominant action of the Sry gen
e. In female mammals, the regulation of X-linked gene dosage at early
embryogenesis is achieved through the inactivation of one of the two X
chromosomes. Here we have investigated the possibility that inactivat
ion of the X chromosome may play a role in male sex determination. We
have shown, using an X-linked lacZ transgenic mouse line, that loss of
beta-galactosidase activity occurs in certain somatic cells of the de
veloping male urogenital ridge. When changes associated with apoptosis
of mesonephric tubules in the developing urogenital ridges are taken
into account, expression of the Xist (X inactive specific transcript)
gene correlates with X inactivation revealed by loss of beta-galactosi
dase activity in very early mesonephric tubule epithelial cells, gonad
al interstitial mesenchymal cells and coelomic epithelial cells.