GastrulationEmbryo, MammalianGastrulaEmbryo, NonmammalianEmbryonic DevelopmentGene Expression Regulation, DevelopmentalBlastocystMesodermEmbryonic and Fetal DevelopmentBody PatterningEctodermEndodermChick EmbryoZygoteMorphogenesisIn Situ HybridizationXenopus ProteinsZebrafishMammalsBlastomeresEmbryo ImplantationEmbryo Culture TechniquesGerm LayersZebrafish ProteinsMolecular Sequence DataCleavage Stage, OvumHomeodomain ProteinsCulture TechniquesTranscription FactorsSignal TransductionEmbryonic InductionPregnancyXenopus laevisAmino Acid SequenceCell LineageMorulaXenopusCell DifferentiationBase SequenceYolk SacNotochordFibroblast Growth Factor 4Fetal ProteinsNodal ProteinCell MovementTotipotent Stem CellsBlastodermRNA, MessengerEmbryo LossNeural CrestFertilization in VitroOctamer Transcription Factor-3OocytesBlastocyst Inner Cell MassBlastulaNervous SystemMice, Inbred CBADNA-Binding ProteinsWnt ProteinsPhenotypeBone Morphogenetic ProteinsModels, BiologicalOrganizers, EmbryonicEmbryonic Stem CellsT-Box Domain ProteinsSea UrchinsPrimitive StreakTrophoblastsGoosecoid ProteinTissue SurvivalSequence Homology, Amino AcidGene ExpressionDrosophila ProteinsStem CellsPleurodelesDrosophilaMice, Inbred ICRTime FactorsMice, Inbred C57BLMutationCloning, MolecularGenomic ImprintingImmunohistochemistryCattleMice, TransgenicGenes, HomeoboxSomitesPluripotent Stem CellsAnimals, Genetically ModifiedActivinsMicroinjectionsCell PolarityGestational AgeProteinsNodal Signaling LigandsMice, KnockoutFibroblast Growth FactorsDNA, ComplementaryBone Morphogenetic Protein 4Cells, Cultured