Total number of nerve fibers, myelin sheath thickness, myelinated fiber diameter and G-ratio. Total number of nerve fibers (A), myelin sheath thickness (B), myelinated fiber diameter (C) and G-ratio (D) at 12 weeks postoperatively. A, B, and C showed that the results from the isograft and ANG + SLC groups were significantly higher than those of the ANG + BM-MSC group. However, D showed no difference in the G-ratio among all groups. The data were shown as the mean ± SEM. *P <0.05, compared with the ANG + BM-MSC group (n = 15).