(A) Photographs of regenerated nerves 9 weeks after implantation. Collagen-filled conduits failed to mediate nerve growth. Conversely, BNIs with collagen, VEGF-MPs or PTN-MPs showed nerve regeneration. (B) Axonal growth in the BNI was confirmed by positive NFP staining. (C) Representative growth inside the microchannels at the middle of the conduit is shown at higher magnification. (D) Double labeling of axons (β-tubulin) and myelin (P0), confirmed nerve regeneration across the gap. (E) The number of axons per channel and (F) distal to the implant showed a mild effect of PTN. *** = p ≤ 0.001. Scale bars: A) 0.5 cm, (B) 350 μm, (C and D) 50 μm.