Ultrastructural study of rabbit sciatic nerve regeneration following experimental excisional transection and autograft reconstruction.

This experimental study presents the ultrastructure of regenerating sciatic nerve of the rabbit, after transection and immediate end to end anastomosis, using perineural fascicular nerve autograft, in a sterile environment. Twenty-four hours, 1, 2, and 6 weeks after the anastomosis, the treated sciatic nerves were exposed and three segments were excised and studied. The first at the region of the graft and the others from the proximal and distal stump of the nerve, in the vicinity of the graft suture. The sections taken from the proximal part showed that the nerve structure was identical with the control. Degeneration and regeneration of nerve fibres were observed on the sections taken from the region of the grafts and from the distal parts. Macrophagic activity appeared mainly one week after the operation. Fibroblastic invasion started 24 hours after operation. A moderate amount of collagen fibres was gradually formed. The fibres were disposed in parallel with the neuraxon. Schwann cells were slightly affected initially but consequently they fully recovered and showed signs of extra-activity of the cytoplasm organelles, e.g., enlargement of the granular endoplasmic reticulum cisternae. The present study showed that the bridging of experimental gaps of rabbit's sciatic nerve, by means of autograft and by use of perineural suturing, was successful. The regenerating nerve fibres were growing through the graft towards the distal part of the nerve. In this process Schwann cells and fibroblastic activity play a key role, which is most favourably influenced by using the technique described in this paper.