Highlights d A transcriptional single-cell atlas of the developing testes during human puberty d Distinctive phases of germ cell differentiation occur during puberty d Identification of a common progenitor for Leydig and myoid cells prior to puberty d Partial reversal of Sertoli and germ cell maturation upon testosterone suppression

In vitro maturation (IVM) of immature oocytes retrieved from surgically resected ovaries has been proposed as a method of fertility preservation in ovarian cancer patients undergoing definitive surgery. While there had been several reports of successful derivation of mature oocytes and or embryos, there have been no reports as yet of successful pregnancies. In this case report, we present a pregnancy and live birth from a young patient, with stage IIIC ovarian cancer, who had undergone fertility sparing surgery. The immature oocytes recovered after oophorectomy were fertilized after IVM. The embryos obtained were cryopreserved and later transferred to achieve a singleton healthy pregnancy leading to a live birth.