Caspase 9 is constitutively activated in mouse oocytes and plays a key role in oocyte elimination during meiotic prophase progression

► To indicate that the apoptotic pathway is constitutively activated in the mouse oocyte. ► To provide evidence that caspase 9 is essential for the elimination of oocytes during meiotic prophase progression. ► To provide evidence that cleaved PARP1 is associated with oocyte loss in the Msh5 null mutant ovary.