In vitro derivation of mouse oocytes from stem cells. Complete in vitro formation of ovarian follicles from embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) (613, 614) used embryonic tissue to obtain somatic cells to support germ cell development, whereas (614, 615) derived somatic support cells from iPSCS demonstrated the complete recapitulation of germ cell development in vitro forming competent oocytes capable of being fertilized and forming embryos. MII, metaphase II; PGCLCs, primordial germ cell-like cells; EpiLCs, epiblast-like cells. Image created with BioRender.com, with permission.