It is highly controversial as to which circulating blood cells are capable of synthesizing TF. In the first review, Osterud describes data generated in his own laboratory and from other groups on the ability of various blood cell types to express TF in health and disease. It seems that the only blood cells capable of synthesizing TF in humans are monocytes. Very low levels of cell surface TF expression may be seen in a few circulating monocytes in healthy individuals. A variety of disease conditions activate monocytes to express TF. In contrast, TF present on activated platelets and granulocytes probably comes from fusion of microvesicles shed by activated monocytes. In the next review, Wolberg and Aleman discuss the role of TF procoagulant activity in fibrin formation and stability of the fibrin network. This review also describes the contribution of cells, plasma and blood flow on thrombin generation and fibrin formation, structure, and stability. Understanding the specific mechanisms by which cells, plasma and blood flow regulate fibrin structure and stability may not only help in understanding hemostasis in finer details, but also be helpful in identifying effective targets for hemostatic and antithrombotic therapies. In general, only a small fraction of the TF found on the cell surface is coagulantly active whereas the vast majority is non-functional, which often is referred to as cryptic TF. How cryptic TF differs from active TF and which mechanisms are responsible for the conversion of cryptic TF to active TF (decryption) has been hotly debated. It has been proposed recently that the cryptic form of TF contains unpaired cysteine thiols at Cys 186 and Cys 209 and that decryption of TF involves the oxidation of Cys186 and Cys209 to form the disulfide bond. Protein disulfide isomerase (PDI) was proposed to be responsible for the oxidation step. However, others have either challenged this hypothesis or found theoretical loopholes in it (Bach and Monroe, Arterioscler Thromb Vasc Biol 29: 1997-8, 2009). Here, Popescu and colleagues summarize these controversies and add one more controversy to this subject. They suggest that PDI could regulate TF activity and binding of coagulation proteins at least in part through changes in lipid asymmetry of the plasma membrane.