How does X inactivation occurs?
1 Answer
The inactive X chromosome is silenced by being packaged in such a way , that it has a transcriptionally inactive structure called heterochromatin
Explanation:
It is understood that X chromosome inactivation is a random process , occurring at about the time of gastrulation in the epiblast. The maternal and paternal X chromosome have an equal probability of inactivation.
In the early blastocysts stage , cells independently and randomly inactivate one copy of the chromosome . Inactivation occurs at the cellular level , resulting in a mosaic expression , in which patches of cells have an inactive maternal X chromosome, while others have an inactive paternal chromosome.
This inactivation event is irreversible during the lifetime of the cell. X inactivation is reversed in the female germline , so that all oocytes contain an active X chromosome.
Sequences at the X inactivation centre , present on the X chromosome, control the silencing of the X chromosome.
