MesodermGastrulaEmbryonic InductionEmbryo, NonmammalianEctodermXenopus ProteinsGene Expression Regulation, DevelopmentalBody PatterningSomitesGastrulationFetal ProteinsIn Situ HybridizationGoosecoid ProteinXenopusXenopus laevisMorphogenesisT-Box Domain ProteinsZebrafishZebrafish ProteinsBlastulaBone Morphogenetic ProteinsHomeodomain ProteinsOrganizers, EmbryonicNervous SystemNodal ProteinActivinsChick EmbryoGenes, HomeoboxTranscription FactorsFibroblast Growth FactorsBone Morphogenetic Protein 4PleurodelesGerm LayersMolecular Sequence DataSignal TransductionPrimitive StreakCell DifferentiationEndodermSea UrchinsCell LineageTailTissue TransplantationEmbryonic DevelopmentBlastodermNeural CrestAmino Acid SequenceInhibinsDNA-Binding ProteinsCoturnixEmbryonic and Fetal DevelopmentBase SequenceQuailHeadBlastomeresDrosophilaTrans-ActivatorsBlastocystOtx Transcription FactorsSOXF Transcription FactorsNodal Signaling LigandsDrosophila ProteinsMicroinjectionsCentral Nervous SystemProteinsTwist Transcription FactorChordataTriturusCell MovementWnt ProteinsSequence Homology, Amino AcidRNA, MessengerTransforming Growth Factor betaMyogenic Regulatory Factor 5Embryo, MammalianNeural PlateCloning, MolecularAnimals, Genetically ModifiedFibroblast Growth Factor 8Repressor ProteinsBone Morphogenetic Protein ReceptorsChordata, NonvertebrateRhombencephalonZygoteExtremitiesLimb BudsIntercellular Signaling Peptides and ProteinsDNA, ComplementaryReceptors, Fibroblast Growth FactorUrochordataLIM-Homeodomain ProteinsBasic Helix-Loop-Helix Transcription FactorsMyoD ProteinGene ExpressionReceptors, NotchEmbryologyHedgehog ProteinsBranchial RegionVertebratesMutationCulture Techniques