Histologic assessment of sciatic nerve regeneration following resection and graft or tube repair in the mouse

The present study determines the number and morphology of myelinated fibers that regenerate after resection of the mouse sciatic nerve. In different groups of mice, a resection of 4 or 6 mm of the sciatic nerve was left unrepaired, repaired with silicone or collagen guides or by an autologous nerve graft of the same or smaller calibre. Regeneration was examined, under light microscopy, 3 months after operation and quantified by morphometric analysis of light micrographs of cross-sectional nerve fibers. The results show that, without repair, few nerve fibers reach the distal nerve stump, while tubulization or autografts allowed better regeneration. Tube repair allowed a comparable degree of regeneration to that of an autograft with 4 mm gaps, but lower with 6 mm gaps. Regeneration was limited with a gap of 6 mm in silicone tubes, but was successful in half the mice with collagen tubes. The size and myelination of regenerated fibers were below normal values in all experimental groups, although they were closer to normal with sciatic autografts than after smaller grafts and tubulization. There were no signs of secondary degeneration in the nerve regenerates within silicone and collagen tubes.