Significantly more Cre⁺ TKO platelets adhered and aggregated on collagen matrices under physiologic flow conditions. Heparinized whole blood from Cre⁺ TKO and Cre⁻ control mice was perfused over a collagen type III surface at a shear rate of 500 seconds⁻¹ (A; 32×/0.40 NA objective) or a collagen type I surface at a shear rate of 1800 seconds⁻¹(B; 60×/0.90 NA water objective). The percentage of surface coverage was significantly higher in perfusion at both lower and higher shear rates in TKO whole blood compared with Cre⁻ controls. Representative pictures of platelet adhesion/aggregation in whole blood (left; n = 9).