LampreysFresh WaterLakesPetromyzonRiversVenous ValvesVaricose VeinsHepatic VeinsGreat Lakes RegionSaphenous VeinVenous InsufficiencyFishesSpiruridaFemoral VeinSuperior ColliculiHagfishesVena Cava, SuperiorEutrophicationOil and Gas FieldsSnowMesenteric Artery, SuperiorWater Pollutants, ChemicalCadaverWater MovementsEcosystemVeinsEnvironmental MonitoringWater MicrobiologySpirurida InfectionsThighGeologic SedimentsIliac VeinCoronary SinusSuperior Vena Cava SyndromeLiver CirculationLiving DonorsSeasonsCerebral VeinsSclerotherapyPhysiology, ComparativePhylogenyBiodiversitySuperior Cervical GanglionMarylandSwimmingUltrasonography, Doppler, DuplexSpinal CordBrazilFish DiseasesVertebratesReticular FormationUltrasonography, Doppler, ColorVascular Surgical ProceduresCichlidsPortal VeinPopulation DensityLiver TransplantationTreatment OutcomeZooplanktonLocomotionPhytoplanktonPyrrolidonecarboxylic AcidAnastomosis, SurgicalTime FactorsPopulation DynamicsBiological EvolutionHepatectomyChordata, NonvertebrateMolecular Sequence Data