Endothelium-derived vasoactive substances in fetal placental vessels

In conclusion, it appears that the endothelium-derived vasoactive substances may have important physiological roles to play in the fetoplacental circulation. They may also play an important role in the pathogenesis of some disease states. The complexity of the umbilical and placental vessels as well as the complexity of the placental vascular bed can slow research progress in this area. It is also important to realize that no single mediator may be able to explain a physiological process, and research workers in this area need to consider possible interactions between the different endothelium-derived vasoactive substances in any physiological or pathological phenomenon.