Organizers, EmbryonicNucleolus Organizer RegionGoosecoid ProteinGastrulaEmbryonic InductionXenopus ProteinsBody PatterningEmbryologyXenopusMesodermEmbryo, NonmammalianGene Expression Regulation, DevelopmentalXenopus laevisZebrafish ProteinsHomeodomain ProteinsNodal ProteinIntercellular Signaling Peptides and ProteinsBone Morphogenetic ProteinsEctodermSilver StainingWnt ProteinsIn Situ HybridizationAmphibiansActivinsBone Morphogenetic Protein 4Nervous SystemMorphogenesisOtx Transcription FactorsProteinsGenes, HomeoboxT-Box Domain ProteinsSignal TransductionFibroblast Growth Factor 8InhibinsGlycoproteinsTransforming Growth Factor betaTranscription FactorsRhombencephalonMicroinjectionsMolecular Sequence DataNotochordHydraMesencephalonAxisNodal Signaling LigandsZebrafishBone Morphogenetic Protein 7HeadRepressor ProteinsTissue TransplantationAmino Acid Sequence