GastrulaSea UrchinsLytechinusEmbryo, NonmammalianGastrulationDigestive System Physiological PhenomenaEndodermEctodermMesodermDigestive SystemFetal Tissue TransplantationMorphogenesisEmbryonic InductionLarvaGene Expression Regulation, DevelopmentalEmbryonic DevelopmentIn Situ HybridizationMolecular Sequence Data