Xenopus ProteinsXenopusXenopus laevisMolecular Sequence DataAmino Acid SequenceEmbryo, NonmammalianGastrulaOvumMicroinjectionsGene Expression Regulation, DevelopmentalBase SequenceCloning, MolecularEmbryonic InductionMesodermMetamorphosis, BiologicalIn Situ HybridizationEctodermRNA, ComplementaryRNA, MessengerSequence Homology, Amino AcidBlastulaCell ExtractsBody Patterning