The potential for the development of non-hormonal contraception has been present in the scientific literature since the 1980s at which point the critical components of gametogenesis of the mammalian oocyte were being classified. Bornslaeger and colleagues discovered that high concentrations of intracellular cAMP, an important second messenger for many biological processes, inhibited resumption of meiosis I in mouse oocytes (3). Later studies demonstrated that phosphodiesterase 3 inhibitors, capable of preventing the breakdown of cAMP, were able to prevent resumption of meiosis in mouse oocytes cultured in vitro (6).