Roles of murine GpIb-V-IX and VWF on platelet-dependent fibrin formation under flow. Adhered platelets from wild-type (WT) mice, transgenic mice lacking the extracellular domain of GpIbα (IL4Rα/GpIbα), or mice deficient in VWF were superfused with autologous plasma at a shear rate of 250 s⁻¹. (A) Representative bright-field images (bars, 20 μm) after 0-60 seconds of fibrin formation, as well as images of OG488-fibrin(ogen). Images were recorded as described.³¹  (B) Lag time to start of fibrin formation. (C) Fractions of fibrin-forming platelets during 25 minutes perfusion. Means ± SE; n = 4-6 mice; ***P < .001 vs WT.