In Vitro Oocyte Maturation TechniquesOocytesOogenesisEmbryo Culture TechniquesMeiosisEmbryo, MammalianFertilizationMetaphaseMaturation-Promoting FactorCumulus CellsEmbryonic DevelopmentGenes, mosBlastocystXenopus laevisMicroinjectionsPolar BodiesOvumParthenogenesisMammalsOvarian FollicleSperm-Ovum InteractionsEmbryo, NonmammalianEgg ProteinsZona PellucidaFertilization in VitroXenopusOvaryOocyte DonationZygoteMeiotic Prophase IOocyte Retrieval