GastrulationGastrulaCell MovementMovementEmbryo, NonmammalianMesodermZebrafishMorphogenesisBody PatterningZebrafish ProteinsGene Expression Regulation, DevelopmentalXenopus ProteinsEndodermEctodermEye MovementsPrimitive StreakIn Situ HybridizationEmbryonic InductionXenopus laevisSignal TransductionNotochordFetal Proteins