Histologic observation and morphometric analysis of regenerated nerves on transverse sections. Light microscopy observation of toluidine blue staining of transversely semithin nerve sections (A1-C1) and transmission electron microscopy of ultrathin nerve sections (A2-C2). A1,A2-normal nerve group as control. B1,B2-autograft group. C1,C2-collagen/PCL NCs group. Normal sciatic nerve (A1, A2) had myelinated nerve fibers with comparatively uniform and large diameter and thick myelin sheath. Regenerated nerves (B1,B2,C1,C2) either from autograft group or collagen/PCL NCs group still presented immature morphologies 4 months postoperatively. Quantitative analysis of myelinated nerve fiber densities (D) showed differences among normal nerve, autograft and collagen/PCL NCs groups and between every two groups were all statistically significant (*p < 0.05), as well as the result analysis of mean inner diameter (axonal diameter) of myelinated nerve fibers showed in E. (Bar in A1,B1,C1 = 20 μm; bar in A2,B2,C2 = 5 μm).