Organizers, EmbryonicNucleolus Organizer RegionEmbryonic DevelopmentCell DifferentiationGoosecoid ProteinGene Expression Regulation, DevelopmentalBody PatterningEmbryonic InductionGastrulaEmbryo, NonmammalianXenopus ProteinsHomeodomain ProteinsZebrafish ProteinsSilver StainingMesodermIn Situ HybridizationEmbryologyZebrafishTranscription FactorsSignal TransductionEmbryo, MammalianXenopusOtx Transcription FactorsMorphogenesisEmbryonic and Fetal DevelopmentMolecular Sequence DataBone Morphogenetic ProteinsWnt ProteinsEctodermNervous SystemFibroblast Growth Factor 8RNA, MessengerNotochordIntercellular Signaling Peptides and ProteinsRhombencephalonCells, CulturedChick EmbryoXenopus laevisNodal ProteinStem CellsCell LineageBlastocystBase SequenceEndodermMesencephalonDNA-Binding ProteinsHydraAmino Acid SequenceHeadGenes, HomeoboxLIM-Homeodomain ProteinsNodal Signaling LigandsPhenotypeCell LineEmbryonic Stem CellsTissue TransplantationAxisTrans-ActivatorsRepressor ProteinsMice, KnockoutProteinsActivinsGene Expression RegulationImmunohistochemistryMutationT-Box Domain ProteinsFetal ProteinsBlastulaTretinoinReverse Transcriptase Polymerase Chain ReactionWnt1 ProteinCell DivisionCell ProliferationTransforming Growth Factor betaHedgehog ProteinsCell NucleolusFibroblast Growth FactorsTranscription, Geneticbeta CateninBone Morphogenetic Protein 4Mice, TransgenicNerve Tissue ProteinsModels, BiologicalMice, Inbred C57BLTime FactorsSilverGene ExpressionSex DifferentiationZygoteGlycoproteinsDrosophila ProteinsPregnancyNuclear ProteinsSequence Homology, Amino AcidEmbryo LossNeuronsCentral Nervous SystemDrosophilaCarrier ProteinsDNA Primers