Circulating factor VIII has two components. (a) Factor VIII c  (Procoagulant protein)This is the smaller component It is synthesized in the liver (main source) and kidney. It is an intrinsic pathway component required for activation of factor X.(b) Von willebrand factor (vWF)This is the larger component It is produced by endothelial cells (main source) and megakaryocytes. It has two major functions.Helps in platelet adhesion by interacting platelet membrane glycoprotein Ib-IX.Stabilizes factor VIIIc.