The repair and reconstruction of nerve defects is a major challenge in the field of peripheral nerve injury.To address short-seg-ment nerve defect repair,end-to-end anastomosis is adopted.For long-segment nerve defect repair,however,autograft remains the gold standard because it contains the structural and biological components ideally matched to the requirements of the peripheral nerve.However,the use of autografts has some disadvantages,including donor site morbidity and the limited availability of expendable autogenous nerve graft tissue.As an altative,an allograft comprising a nerve guide/conduit,can be used to treat nerve defects up to a few centimeters long (Meek and Coert,2008).We previously refined the extraction method for this (Sondell et al.,1998) and were able to obtain chemically extracted acellular nerve allografts from canine and human sciatic nerves,which have more interfascicular epineurium,and a thicker perineurium and epineurium than rat sciatic nerves.After verifying low immunogenicity of these constructs,we successfully repaired 5-cm sciatic nerve defects in a canine model (Zhong et al.,2007).Furthermore,21 patients with nerve defects were successfully treated with chemically extracted acellular nerve allografts,with all patients regaining sensation and motion (Guo et al.,2008).As a result,we believe that the best altative for peripheral nerve gap repair is a nerve conduit,which recreates in vivo structures and contains essential components needed for peripheral nerve regeneration (Zhou et al.,2014).