Oocytes represent the start material for all mammalian development. With the introduction of DNA from the sperm, the oocyte is transformed into a totipotent cell that gives rise to all tissues of the body and the placenta. Therefore, understanding how the oocyte works will give great insight what is required to realize the full developmental potential of any cell. Here, we begin to dissect mechanisms that make the oocyte so unique. We find a protein that had previously been implicated in male infertility is also required for the late female germ cell, the oocyte. In its absence, the oocyte cannot mature. Furthermore, we show that this protein regulates hundreds of genes by inducing their encoded RNAs to produce protein. This fundamental mechanism is likely to be used over and over again in human development. Therefore, these experiments provide a start point for tackling similar questions in stem cells in general.