Haemostatic Plug Formation

When the vascular endothelium is disrupted, platelets adhere to the exposed subendothelial tissue (mainly collagen). Adhesion requires von Willebrand Factor (vWF), a protein secreted by endothelial cells and also contained in platelet granules. Von Willebrand factor binds to platelet surface receptors (glycoproteins GPIb) and facilitates the adhesion of platelets to the subendothelium.