Initiating pathway of in vitro coagulation. For in vivo considerations, the pathway is also referred to as the tissue factor pathway. Physiologically Tissue Factor from extravascular sources and FVII from blood are key components and the resulting complex, when assembled on activated monocytes or perturbed endothelial cells, has two substrates: FX and FIX. For in vitro testing, a thromboplastin reagent is the source for Tissue Factor (complexed with phospholipid). The PT is affected by FVII and components in the common pathway of coagulation. The slide show entitled Tissue Factor Pathway (Extrinsic) with Common Pathway (PT) shows the components of this pathway.
