Representative images from level 4 of the axonal regeneration and myelination in repairs with the A, D Col and B, E SIS conduits (immunohistochemistry stain [NF and MBP]; magnification ×400; scale bars, 50 μm). The regenerating nerve cable density was significantly different between groups at level 3 and level 4 (P = .006). C The NF staining density was significantly different at level 4 for the SIS conduit group compared to the Col conduit group. D, F The stain density in the central region of the regenerating cable was significantly different between groups at level 3 and level 4 (P = .027) (MBP stain; magnification ×400; scale bars, 50 μm).