In Vitro Oocyte Maturation TechniquesOocytesEmbryo Culture TechniquesOogenesisMeiosisMetaphaseCumulus CellsFertilizationXenopus laevisMaturation-Promoting FactorGenes, mosProto-Oncogene Proteins c-mosMicroinjectionsParthenogenesisEmbryonic DevelopmentBlastocystOocyte DonationXenopusOvumOocyte RetrievalSperm-Ovum InteractionsOvarian FollicleFertilization in VitroOvary