Starting out with ESCs and iPSCs from female mice, they tinkered with a few genes to induce epiblast-like cells (epiLCs) and then PGCLCs. They then aggregated those cells with embryonic gonadal somatic cells, which support the development of germ cells, to create "reconstituted ovaries" in vitro. The PGCLCs proliferated well, progressing similarly to PGCs in embryonic ovaries, and showed meiotic potential.