Reconstituting reproduction in culture Research on in vitro gametogenesis (IVG) aims to reconstitute germ cell development, oogenesis and spermatogenesis, in culture. Saitou and Hayashi review some of the recent developments in mammalian IVG. Advances in methods and culture conditions in mice to generate mature oocytes and spermatocytes from pluripotent stem cells have informed similar studies with nonhuman primate and human cells, but differences among species are clear. IVG has great potential for reproductive medicine, including novel diagnosis and modeling of infertility. The realization of human IVG requires further intensive efforts, but as technical hurtles are overcome, careful consideration must be given to the potential application of methods for reproductive purposes. —BAP