[Endothelium and hemorrhages].

Normal endothelium, as well as megakaryocytes, produces and secretes von Willebrand factor which plays a pivotal role in haemostasis. It mediates platelet adhesion and shear-stress-induced aggregation at the site of vessel wall injury and also serves as a carrier protein of factor VIII, an essential cofactor in coagulation. The quantitative or qualitative abnormalities of von Willebrand factor lead to von Willebrand disease, the most common congenital bleeding disorder. Over the past few years major progress in the knowledge of the synthesis, structure and functions of von Willebrand factor have led to improve the diagnosis and treatment of the different molecular forms of von Willebrand disease.