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Science

Reconstituting a human ovary Human pluripotent stem cells (hPSCs) have been induced into human primordial germ cell–like cells (hPGCLCs) in vitro, the first step toward human in vitro gametogenesis. Yamashiro et al. went a step closer to generating mature gametes by culturing hPSCs with mouse embryonic ovarian somatic cells in xenogeneic reconstituted ovaries (see the Perspective by Gill and Peters). Over a period of 4 months, hPGCLCs underwent hallmark epigenetic reprogramming and differentiated progressively into cells closely resembling human oogonia, an immediate embryonic precursor for human oocytes. This study creates opportunities for human germ cell research and provides a foundation for human in vitro gametogenesis. Science , this issue p. 356 ; see also p. 291

Generation of human oogonia from induced pluripotent stem cells in vitro