Figure 1

Schematic representation of the main stages of mouse oogenesis (upper drawing) and of the three in vitro culture methods of endogenous germ cells (medial drawings) capable of producing metaphase II (MII) oocytes that after in vitro maturation (IVM) and in vitro fertilization (IVF) or nuclear transfer (NT) generated live offspring; most essential components of the culture media are also reported. The upper drawing displays the process of oogenesis from 12.5 days post-coitum (dpc) and folliculogenesis, including the essential stages of embryonic primordial germ cells (PGCs) at 12.5 dpc, primordial follicles at birth, and the formation of secondary and antral follicles at 7 and 14 days post-partum (dpp), development of mature gametes as oocyte–granulosa cell complexes, oocyte meiosis and IVF. The medial figure shows the offspring through in vitro culture with 1 dpp ovary by O’Brien et al. (a) and fetal ovary at 12.5 dpc by Obata et al. (b) and Morohaku et al. (c) The lower panel shows the different cell types annotated