Nerve regeneration through preformed pseudosynovial tubes. A preliminary report of a new experimental model for studying the regeneration and reorganization capacity of peripheral nerve tissue.

In a two-stage procedure the pseudosynovial sheath, formed around a silicone rubber rod placed in the back of rats, was used as a free "tube-graft" to bridge freshly cut gaps of 12 mm length in the sciatic nerve. The tube was kept open by a thin metal spiral, originally implanted around the silicone rubber rod. In this model the regenerating nerve fibers grew into an "open" space formed inside the pseudosynovial tube. The tissue formed in the tube was analyzed after 3 months by light and electron microscopy. Within the tube a new nerve trunk was formed, comprising closely packed myelinated and nonmyelinated fibers organized in fascilcles. The fascicles were surrounded by regenerated perineurim, and the new nerve was surrounded by an epineurium-like sheath. An electromyogram recorded from the flexor muscles of the foot confirmed motor reinnervation. The findings are discussed in view of current concepts of nerve regeneration.