Figure 1.

Specification of primitive ovarian granulosa cells from ESCs in vitro, which are capable of interacting with early germ cells to initiate folliculogenesis. Differentiation of mouse ESCs engineered to express green fluorescent protein (GFP) driven by a ΔPE-Pou5f1 gene promoter (germ cell marker) and DsRed driven by a Foxl2 gene promoter (primitive granulosa cell marker) leads to the in-vitro formation of ovarian follicle-like structures containing GFP-positive oocytes surrounded by DsRed-expressing granulosa cells. Reproduced from Woods et al.¹³⁹