MesodermGastrulaEmbryonic InductionEctodermXenopus ProteinsGoosecoid ProteinEmbryo, NonmammalianNodal Signaling LigandsGene Expression Regulation, DevelopmentalBody PatterningXenopusZebrafish ProteinsNervous SystemFetal ProteinsXenopus laevisNodal ProteinHomeodomain ProteinsBone Morphogenetic ProteinsIn Situ HybridizationMorphogenesisActivinsT-Box Domain ProteinsZebrafishGenes, HomeoboxPipidaeSomitesEnzyme InductionNotochordOrganizers, EmbryonicTranscription FactorsSignal TransductionBone Morphogenetic Protein 4Bone Morphogenetic Protein ReceptorsMolecular Sequence DataWnt ProteinsTrans-ActivatorsDrosophila ProteinsCell DifferentiationInhibinsDNA-Binding ProteinsRNA, MessengerBase SequenceRepressor ProteinsTransforming Growth Factor betaDrosophilaChick EmbryoAmino Acid SequenceReceptors, Growth FactorProteinsGastrulationEndodermFibroblast Growth FactorsGlycoproteinsCoturnixQuailSequence Homology, Amino AcidTwist Transcription FactorEmbryonic and Fetal DevelopmentCell LineageFibroblast Growth Factor 8Cells, CulturedPrimitive StreakGerm LayersNeural CrestEmbryonic DevelopmentEmbryo, MammalianExtremitiesMutationGene ExpressionLimb BudsBasic Helix-Loop-Helix Transcription FactorsTailTranscription, GeneticGene Expression RegulationHeadTime FactorsCell LineTissue TransplantationBranchial RegionAvian ProteinsApoptosisCell MovementVisceraHeartModels, BiologicalPromoter Regions, GeneticDNA PrimersAnimals, Genetically ModifiedBlastodermReverse Transcriptase Polymerase Chain ReactionPhenotypeMice, Inbred C57BLReceptors, Fibroblast Growth FactorEmbryonic Stem CellsLeft-Right Determination FactorsHedgehog ProteinsCloning, MolecularProto-Oncogene ProteinsMyogenic Regulatory Factor 5Immunohistochemistry