In female mammals, the process of dosage compensation occurs during early embryonic development. As a result of this, one of X-chromosomes becomes transcriptionally inactive. This process is accompanied by chromatin remodeling on inactivated X-chromosome, providing transcriptional silencing of the genes and maintenance of their inactive state. In the present review, the dynamics of modifications occurring during embryonic inactivation, their distribution over the inactive X-chromosome, interaction, and the role in establishing and maintening the inactive state are discussed. As an illustration, modifications on the inactive X-chromosome of the Microtus common vole are presented.