Novel regulatory proteins have been identified within oocytes that are crucially involved in folliculogenesis. One of the most exciting oocyte signaling molecules is a novel member of the transforming growth factor beta (TGF-beta) superfamily, growth differentiation factor 9 (GDF-9). Loss-of-function studies have established that GDF-9 is obligatory for proper folliculogenesis and fertility in female mice. The current challenges are to understand how oocyte morphogens regulate folliculogenesis and how their actions and interactions are integrated into the overall processes of physiology and pathophysiology. Who would have thought that oocyte morphogens would be so crucial for reproduction?