GPVI-dependent platelet spreading on D-dimer. (A) Glass coverslips were coated overnight with fibrinogen, fibrin, or D-dimer. Mouse platelets (ptl; 20 × 10⁹/L) were allowed to spread on coated coverslips followed by staining for actin with Alexa-488 phalloidin. Scale bar, 5 μm. The figure is representative of 3 similar experiments. (B) Quantification of platelet surface area and platelet count per millimeter squared (n = 3). In each independent experiment, 5 random pictures were analyzed (100 platelets in total). The results are shown as mean ± standard deviation. *P < .05, ***P < .001 compared with fibrinogen; ^#P < .05, ^###P < .001 compared with wild type (WT).