Organizers, EmbryonicNucleolus Organizer RegionGoosecoid ProteinEmbryo, NonmammalianBody PatterningGastrulaEmbryonic InductionEmbryo, MammalianXenopus ProteinsChick EmbryoGene Expression Regulation, DevelopmentalSilver StainingEmbryologyZebrafish ProteinsHomeodomain ProteinsOtx Transcription FactorsMesodermXenopusZebrafishBlastocystIn Situ HybridizationFibroblast Growth Factor 8NotochordEmbryo ImplantationNodal ProteinEctodermEmbryonic DevelopmentRhombencephalonMorphogenesisXenopus laevisWnt ProteinsHydraBone Morphogenetic ProteinsMesencephalonNodal Signaling LigandsNervous SystemHeadIntercellular Signaling Peptides and ProteinsAxisTissue TransplantationBlastomeresLIM-Homeodomain ProteinsTranscription FactorsEndodermGenes, HomeoboxSilverCell NucleolusSignal TransductionEmbryonic and Fetal DevelopmentWnt1 ProteinActivinsBlastodermLeft-Right Determination FactorsMolecular Sequence DataT-Box Domain ProteinsZygoteEmbryo LossProteinsMetencephalonFibroblast Growth FactorsGlycoproteinsBlastulaAmino Acid SequenceFetal ProteinsBone Morphogenetic Protein 4Fertilization in VitroMicroinjectionsPregnancyCleavage Stage, OvumTwins, ConjoinedRepressor ProteinsCulture TechniquesRNA, MessengerTrans-Activatorsbeta CateninTransforming Growth Factor betaBase SequenceMatrix Attachment Region Binding ProteinsDNA-Binding ProteinsDrosophilaInhibinsHepatocyte Nuclear Factor 3-betaAmphibiansHedgehog ProteinsCell DifferentiationDrosophila ProteinsCentral Nervous SystemSilver NitrateAnimals, Genetically ModifiedNeural PlateSomitesMutationQuailCell LineageNerve Tissue ProteinsChromosomesOocytesProsencephalonTectum MesencephaliTail