Comparison of two mouse models of venous thrombosis. In the inferior vena cava stenosis model of venous thrombosis, the inferior vena cava is ligated to reduce blood flow by ∼90%. Platelets, FXII, and neutrophils contribute to immune thrombosis. In the spontaneous venous thrombosis model, mice are treated with small interfering RNAs to reduce levels of the anticoagulants antithrombin and protein C. Platelets contribute to thrombosis in this model, whereas there is no role for neutrophils, and decreasing FXII increases thrombosis. NET, neutrophil extracellular trap. Professional illustration by Somersault18:24.