Reports

The germ cell lineage in mammals originates from pluripotent epiblasts as primordial germ cells (PGCs) and undergoes sexually dimorphic de-velopment, generating spermatozoa in males and oocytes in females. These cells fertilize to form zygotes with full developmental potential, serving as the foundation of the mammalian life cycle. We have shown previously that embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) from male (XY) mice are induced into epiblast-like cells (EpiLCs), which are in turn induced into primordial germ cell–like cells (PGCLCs) with proper function for spermatogenesis and offspring production (1). Considering the differences between male (XY) and female (XX) ESCs, including those at the epigenetic level (2), together with the markedly different mechanisms of male and female germ cell development (3), it remains a fundamental challenge to determine whether our system reconstitutes the female developmental pathway and whether PGCLCs serve as precursors for fully functional oocytes