Final answer:
Von Willebrand factor (vWF) assists platelet adhesion by binding to exposed collagen and endothelial lining. It is produced by endothelial cells and megakaryocytes in the bone marrow.
Step-by-step explanation:
Von Willebrand factor (vWF) is a glycoprotein in the blood plasma that helps stabilize the growing platelet plug. It assists in platelet adhesion by binding to the exposed collagen and endothelial lining at the area of vessel rupture. This binding helps the platelets to clump together, become spiked and sticky, and adhere to the damaged blood vessel. vWF is produced by endothelial cells and megakaryocytes in the bone marrow.