Increased bleeding time and unstable thrombi in the absence of platelet apoptosis. (A) Representative images of platelets from Bak^+/+Bax^+/+, Bak^−/−Bax^fl/fl, and Bak^−/−Bax^{Pf4∆/Pf4∆} mice visualized by transmission electron microscopy. Scale bar, 2 µm. Dense granule (DG) and α granule (AG) are indicated by arrows. (B) Tail bleeding time assessed after tail incision (5 mm long and 1 mm deep). Bleeding was monitored by blotting with filter paper every 30 sec. Each symbol represents an individual mouse. (C) Tail bleeding time into 37°C saline (3-mm tail amputation) and (D) blood loss (hemoglobin levels). Blue bars in C represent the initial cessation of bleeding, and red bars represent length of rebleeding. n = 8 mice per genotype. (E-H) Electrolytic thrombosis model. (E) Time to initial occlusion, (F) stability of blood flow, (G) vessel patency, and (H) blood flow (60 minutes postinjury). n = 9 mice per genotype. Data are presented as mean ± SEM. Unpaired Student t test with 2-tailed P values. *P < .05; **P < .005; ***P < .001; n.s., not significant.