In vitro oogenesis breaks free of the ovary.

In this issue of Developmental Cell, Nosaka et al. differentiate mouse pluripotent stem cells to large germinal vesicle-stage oocyte-like cells in the absence of ovarian somatic cells. Their paradigm advances the field toward clinical translation and offers insights into oogonial cyst breakdown, X chromosome dynamics, and requirements for oocyte growth and meiotic resumption.