Tiam Mana Saffari

13 GENERAL INTRODUCTION 1 peripheral tissues and share several anatomical and functional characteristics 10 . The embryologic formation of vessels is called angiogenesis and describes endothelial cells to migrate toward and align with peripheral nerves in response to vascular endothelial growth factor-A (VEGF-A) 10 . VEGF is a potent multifunctional cytokine that stimulates angiogenesis and plays a large role in revascularization after injury to the nerve 11 . Figure 1. Schematic illustration of a peripheral nerve. The peripheral nerve is depicted with groups of fascicles that are surrounded by the epineurium. Each fascicle of endoneurium contains up to several thousands of axons. The nerve fascicle (depicted with the square) is enveloped by the perineurium. Blood is supplied by a network of capillary-like micro vessels derived from arterioles and venules, which are branches of major limb vessels. The zoomed image depicts the close relationship of vessels and axons. When the nerve is injured, vascular endothelial cells guide the regeneration of peripheral nerve axons by producing vascular endothelial growth factor (VEGF, green dots) to induce angio- genesis. With permission of the Mayo Foundation, Copyright Mayo Foundation. All rights reserved.