[Meiotic inactivation of sex chromosomes in mammals].

During meiosis, heteromorphic mammalian X and Y chromosomes in males undergo transcription silencing and form a compact structure, the XY body, containing specific modifications of the chromatin. In this review, we consider the dynamics of sex chromosome inactivation and discuss the suggestion that the paternally inherited X chromosome preserve inactivated state in zygote. This state results from meiotic silencing and is prone to imprinted inactivation, which his observed in mammalian females at early embryogenetic stages.