The road to maturation: somatic cell interaction and self-organization of the mammalian oocyte.

Mammalian oocytes go through a long and complex developmental process while acquiring the competencies that are required for fertilization and embryogenesis. Recent advances in molecular genetics and quantitative live imaging reveal new insights into the molecular basis of the communication between the oocyte and ovarian somatic cells as well as the dynamic cytoskeleton-based events that drive each step along the pathway to maturity. Whereas self-organization of microtubules and motor proteins direct meiotic spindle assembly for achieving genome reduction, actin filaments are instrumental for spindle positioning and the establishment of oocyte polarity needed for extrusion of polar bodies. Meiotic chromatin provides key instructive signals while being 'chauffeured' by both cytoskeletal systems.