MesodermOrganizers, EmbryonicEmbryonic InductionXenopus ProteinsNucleolus Organizer RegionGastrulaActivinsXenopusGoosecoid ProteinBody PatterningEmbryo, NonmammalianGene Expression Regulation, DevelopmentalFetal ProteinsEctodermInhibinsXenopus laevisNodal ProteinT-Box Domain ProteinsIn Situ HybridizationFibroblast Growth FactorsNodal Signaling LigandsZebrafish ProteinsBone Morphogenetic ProteinsMorphogenesisActivin ReceptorsSignal TransductionLeft-Right Determination FactorsZebrafishBone Morphogenetic Protein 4Homeodomain ProteinsGastrulationTransforming Growth Factor betaMolecular Sequence DataReceptors, Fibroblast Growth FactorTranscription FactorsWnt ProteinsMicroinjectionsSomitesCell DifferentiationEnzyme InductionBase SequenceRNA, MessengerDNA-Binding ProteinsBlastocystIntercellular Signaling Peptides and ProteinsAmino Acid SequenceEmbryonic and Fetal DevelopmentProteinsTrans-ActivatorsChick EmbryoGrowth SubstancesEndodermFibroblast Growth Factor 8Silver StainingReceptors, Growth FactorGenes, HomeoboxNervous SystemEmbryologyOtx Transcription FactorsDNA PrimersPhenotypeHeadGene ExpressionTranscription, GeneticMutationTissue TransplantationFibroblast Growth Factor 2Reverse Transcriptase Polymerase Chain ReactionRhombencephalonCloning, MolecularQuailCoturnixAxisWnt1 ProteinCell LineageDrosophilaDrosophila ProteinsLIM-Homeodomain ProteinsEmbryonic DevelopmentBlastulaBlastodermTailRepressor ProteinsNotochordGerm LayersMesencephalonHydraEmbryo, MammalianNeural CrestCells, CulturedHedgehog ProteinsTime FactorsLimb BudsTwist Transcription FactorExtremitiesBasic Helix-Loop-Helix Transcription FactorsModels, BiologicalGlycoproteinsAvian ProteinsAnimals, Genetically Modified