X-chromosome inactivation occurs at different times in different tissues of the post-implantation mouse embryo

Nat Genet. 1993 Feb;3(2):170-4. doi: 10.1038/ng0293-170.


During mammalian development, one of the two X chromosomes in female embryos is randomly inactivated in the somatic cell in order to achieve gene dosage compensation. But is X inactivation established simultaneously or is it accomplished over time in a lineage-dependent fashion? We have examined this question in mouse embryos carrying an X-linked lacZ transgene. This transgene is subject to inactivation and the loss of beta-galactosidase activity provides a direct indication of X inactivation in individual cells. We find that X inactivation proceeds with different schedules in different somatic tissues, and the notochord, the heart, cranial mesoderm and the hindgut are among the last tissues to undergo X inactivation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dosage Compensation, Genetic*
  • Embryonic and Fetal Development / genetics*
  • Female
  • Gene Expression
  • Genetic Linkage
  • Gestational Age
  • In Vitro Techniques
  • Lac Operon
  • Mice
  • Mice, Transgenic
  • Organ Specificity
  • Pregnancy
  • X Chromosome
  • beta-Galactosidase / genetics


  • beta-Galactosidase