Figure 1.

Illustrations of oocyte prophase I arrest and the strategy for expressing the Cdk1^AF allele in dormant and growing oocytes. (A) All of the dormant and growing oocytes remain in prophase I arrest with GV and are meiotically incompetent. Only the fully grown oocytes are meiotically competent and have the capability of resuming meiosis. Gdf9-Cre recombinase starts to be expressed in dormant oocytes in primordial follicles, and Zp3-Cre starts to be expressed only in growing oocytes in developing follicles. GV, germinal vesicle. (B) Cdk1 remains in an inactive state due to its phosphorylation at T14 and Y15 by Wee1/Myt1. Cdk1 activation requires dephosphorylation of T14 and Y15 by Cdc25. Cdk1 with mutation of T14 and Y15 to A14 and F15 cannot be phosphorylated and therefore Cdk1 activity cannot be inhibited by Wee1/Myt1. (C) Oocyte-specific expression of the Cdk1^AF allele starting from dormant oocytes as mediated by Gdf9-Cre or starting from growing oocytes as mediated by Zp3-Cre.