Transcriptional and epigenetic control of germline competence and specification.

In mammals, germline specification is induced during early embryogenesis when competent cells respond to extrinsic signals and form primordial germ cells (PGCs), the precursors of the gametes. The fusion of the two types of gametes, the egg and the sperm, gives rise to a new organism and closes the germline cycle. With the entry of the germline, the PGCs are separated from the soma and thus ensure the self-perpetuation of the species. Using the mouse as a model of mammalian embryogenesis, in this review we will focus on the transcriptional and epigenetic changes that regulate the initial steps of germline development, namely germline competence and PGC specification.