Platelets PS limits thrombus propensity and affects thrombus composition. (A-C) TF-induced venous thromboembolism using high dose of recombinant TF in A (1/2 dilution of Innovin; ∼4.3 nM TF) and low dose in panels B and C (1/8 dilution of Innovin; ∼1.1 nM TF). In panel A, no differences were found between Pros1^lox/loxPf4-Cre⁻ (straight line; n = 14) and Pros1^lox/loxPf4-Cre⁺ (dashed line, n = 14). (B) Pros1^lox/loxPf4-Cre⁺ (dashed line; n = 14) and Pros1^lox/− (dotted line, n = 14) mice showed higher mortality than Pros1^lox/loxPf4-Cre⁻ (straight line; n = 14) mice. (C) Thrombus formation in FeCl₃-injured mesenteric arterioles recorded by intravital microscopy in Pros1^lox/loxPf4-Cre⁻ and Pros1^lox/loxPf4-Cre⁺ mice, representative experiment (n = 7/genotype). Recorded occlusion time is shown in panel D. (E-G) Thrombi were collected 20 minutes after FeCl₃ challenge and processed to confocal microscopy, pictures were taken close to the lesion side and on the top of the thrombus as shown in panel E. Confocal microscopy of the thrombi analyzed 20 minutes after the FeCl₃ injury and stained for FXa and thrombin and CD41 (F; scale bar, 50 μM) as well as for insoluble fibrin, CD41, and CD62p (G; scale bar, 50 μM). Data are expressed as mean ± SEM. *P < .05; **P ≤ .01; ***P ≤ .001.