<unk><unk> <unk>  cell (PGC)<unk>  is the process of distribution of<unk> <unk>  cells throughout the embryo during embryogenesis.
Primordial germ cell migration
Zona hatching
Eutherian fetoembryonic defense system 
Fetal resorption
Control of chromosome duplication
Epigenetics in stem-cell differentiation
Onselling of sperm
Development of the reproductive system