Activin Receptors, Type IIActivin ReceptorsActivinsActivin Receptors, Type IMyostatinInhibinsInhibin-beta SubunitsFollistatinReceptors, Growth FactorSmad2 ProteinReceptors, Transforming Growth Factor betaTransforming Growth Factor betaNodal ProteinSignal TransductionBone Morphogenetic ProteinsSmad ProteinsRNA, MessengerGrowth Differentiation FactorsBone Morphogenetic Protein Receptors, Type IBone Morphogenetic Protein Receptors, Type IIMesodermSmad3 ProteinProtein-Serine-Threonine KinasesSmad4 ProteinGrowth SubstancesIn Situ HybridizationEmbryonic InductionGene Expression Regulation, DevelopmentalGene ExpressionXenopus ProteinsMolecular Sequence DataMyositis OssificansXenopusGlycoproteinsTrans-ActivatorsCell DifferentiationGranulosa Cells