Objective:To study the role and effect of Schwann cells (SCs) remyelination in contused spinal cord.Methods:Green fluorescence protein expressing-SCs were transplanted into the epicenter,rostral and caudal tissues of the injury site at 1 week after the spinal cords were contused.At 6 weeks,the spinal cords were removed for cryosections,semithin sections and ultrathin sections,and then immunocytochemical staining of myelin basic protein (MBP),P0 protein (P0) and S 100 protein (S100) was carried out on the cryosections.Qualitative and semiquantitative analyses were performed on the cryosections and semithin sections.Ultrastructure ofmyelinated fibers was observed on the ultrathin sections under electron microscope.Results:Transplanted SCs and myelinated fibers immunocytochemically labeled by MBP,P0 as well as S100 distributed in whole injured area.The quantity of myelinated fibers labeled by the three myelin proteins showed no statistical difference,however,which was significantly larger than that of controls.On the semithin sections,the experimental group demonstrated more myelinated fibers in the injured area than the controls,but the fibers had smaller diameter and thinner myelin sheath under electron microscope.Conclusion:SCs can promote regeneration of injured nerve fibers and enhance remyelination,which may be histological basis of SCs-mediated functional repair of injured spinal cords.