Adhesion and spreading of S14 platelets on immobilized collagen under static and shear conditions. (Ai) Washed human platelets (1 × 107/mL) from control (Control) or patient (S14) were allowed to adhere and spread on immobilized fibrinogen (Fibrinogen), VWF (VWF), and collagen (Collagen) for 45 minutes at 37°C. Adherent platelets were fixed, permeabilized, and stained with rhodamine-phalloidin, then imaged using fluorescence microscopy, and cropped representative images are shown. Images are taken from 1 experiment, representative of 2. (ii) Graphs show the number of platelets adherent to the thrombogenic matrix and the number of platelets that had undergone some change in shape, recorded as a percentage of spread platelets, mean ± SEM. ▪ indicates control; □, S14. (B) Whole blood was obtained from control (Control); patient (S14) or whole blood from control donor was diluted with autologous platelet-poor plasma and red blood cells (Control - normalized) and perfused over collagen- (100 μg/mL; top row) or VWF-coated (100 μg/mL; bottom row) capillary tubes at a shear rate of 800 s^-1 or 1800 s^-1, respectively, for 2 to 5 minutes. Nonadherent platelets were removed by perfusion with Tyrode buffer. Three to 5 fields were imaged per capillary slide, and representative images are shown (× 63 objective).