Background & Objectives: Formation of myelin depends on maturation and development of the axonal cytoskeleton andmitochondria. Collagen gel can specifically play role in the regulation and development of axonal cytoskeleton.

  Methods: This research is an experimental study in which forty eight male rats (200-250g) were used. After axotomy, 1 cm segment of the sciatic nerve in rats was removed, and the gap was then bridged by one of the four following methods: polyvinylidene fluoride or PVDF + Collagen gel, Autograft, sham and control. Sciatic nerve was studied by electron microscope by the end of the 4^th week and the 12^th week.

  Results: By the end of the 4^th week after the regeneration the number of unmyelinated axons in autograft and Collagen Gel was not significant, by the end of the 12^th week, the number of unmyelinated axons in autograft group was superior to that of nerve growth factor group (P<0.01). After 12 weeks of regeneration, microtubular density values of normal and autograft groups were not statistically different. The cristae of axonal mitochondria in experimental groups are orientate parallel with its long dimension.

  Conclusion: The results of study indicated that because of its positive effect on the growth and development of microtubules and mitochodria, collagen Gel combination with PVDF can be used to repair peripheral nerve injuries.