BlastocystGastrulaPleurodelesMorulaMicromanipulationEmbryo, NonmammalianEmbryonic DevelopmentBlastulaEmbryonic and Fetal DevelopmentSea UrchinsMesodermXenopus laevisBlastomeresEctodermCryopreservationMorphogenesisTrophoblastsEmbryonic InductionTight JunctionsCulture TechniquesGene Expression Regulation, DevelopmentalCell PolarityXenopus ProteinsEmbryo TransferPregnancyFertilization in VitroFibronectinsMice, Inbred StrainsEmbryo, MammalianCell MovementCell AdhesionMicroscopy, ElectronCell DifferentiationTime FactorsRNA, MessengerCells, Cultured