N-1 rule = all but one x chromosome is silenced. Xist rna is the master regulator of x inactivation. About 50-100 transcripts that can coat inactive x chromosome. With each round of replication, ther"es the inehreitance of transcriptional repression that is passed onto daughter cell. One of the earliest events is the upregulation of xist gene and can be fisualised with. When x inactivation hasn"t happened there"s 2 active x, and then xist upregulation and transcriptional silencing of one x chromosome -> inactive x, on previously active x, xist. Rna covers it (?) and now it"s silenced. After x inactivation ther"es formation of inactive x chromosome which is epigenetically different from the active x. Some silent marks are shown in red and lacks active mark. Can visualise the enrichment of the modifications on inactive x chrosoome. During x initiation, almost all x linked genes are silenced.