PlacentationTrophoblastsPlacentaPregnancyEmbryo ImplantationDeciduaUterusPlacenta DiseasesPregnancy ProteinsPlacental CirculationChorionic VilliPregnancy Trimester, FirstPre-EclampsiaEndometriumPregnancy, AnimalPlacenta AccretaEmbryo LossViviparity, NonmammalianPhysiology, ComparativeUterine ArteryMarsupialiaChorionGestational AgeXenarthraYolk SacMaternal-Fetal ExchangeRodentiaFetal DeathAllantoisFetal Growth RetardationExtraembryonic MembranesImmunogenetic PhenomenaEmbryonic DevelopmentIn Situ HybridizationFetal Development