Structural and Ultrastructural Study of Motor Neurons Following Sciatic Nerve Repair by Epineural Suture, Autograft and Nerve Guidance Channel in Adult Rat

Introduction & Objective: Much interest has been focused on the development of alternative instrument for bridging the nerve gaps. In the present study we used poled polyvinelidene fluoride (PVDF) tube filled with nerve growth factor (NGF) and collagen gel as a substitute for nerve autograft and compared the results with other current surgical techniques. Materials & Methods: In this experimental study, 40 male Wistar rats each weighing 200-250 g were randomly divided in five groups nerve guidance channel, autograft, epineural suture, axotomy and sham operation. In nerve guidance channel groups, a 10 mm piece of left sciatic nerve was transected and this gap was repaired by PVDF tube containing NGF 7s (100 ng) and collagen gel (1.28 mg/ml). In autograft group, the 10 mm piece was 180° rotated and sutured to two nerve ends. In epineural suture group, left sciatic nerve in the middle thigh was transected then sutured end to end. In axotomy group, left sciatic nerve was transected in the middle thigh and was not repaired. After two months, left ventral L4-6 segments of spinal cord was removed and semi-thin and ultra-thin preparation for light and electron microscope were done. Contra-lateral side of spinal cord segments was used as control in all groups. Results: After two months we observed motor neuron atrophy and shrinkage, cytoplasmic vacouels and piknotic neurons in different surgical groups, but it was more intense in axotomy group. These changes were less in epineural suture group than in autograft and nerve guidance channel groups. In sham and control groups no changes were observed. In addition, increased nuclear condensation, nuclear membrane folding, central and marginal chromatin clumping in spinal motor neuron were observed in surgical groups mainly in axotomy group. Conclusion: According to the results, any type of injury to the sciatic nerve can cause cell changes and finally cell death in the spinal motor neurons. Using PVDF with NGF and collagen gel reduced cell changes at the level of autograft.