The most critical step of mammalian embryogenesis in securing the future of the species comes just days after fertilization, and immediately after implantation into the uterine wall. At this time, a small subset of epiblast cells receives an inductive signal from neighboring extraembryonic tissue, the germ lineage is specified, and the resulting primordial germ cells (PGCs) are given full potential to eclipse the lifetime of the developing embryo in which they reside (1). After specification, PGCs migrate along the hindgut and through the dorsal mesentery to the genital ridge, the precursor to the gonad. Once there, PGCs commit to their germ cell fate and become encompassed by the developing gonad, where germline stem cells proliferate and ultimately undergo meiosis to produce oocytes and sperm (Fig. 1). In PNAS, Nicholls et al. (2) describe events that transpire upon PGC colonization of the genital ridge.