[Electron microscopic study on the degeneration and regeneration of the rat liver nerve fibers].

With advances in liver transplantation, attention has been directed to the regeneration of hepatic nerves. In this study, examination is made of ultrastructural degeneration and regeneration of hepatic nerves following severance at a point 8 mm proximal to the portal fissure in the rat liver. Immediately after the operation, distal nerve axons swelled and showed the disappearance of microtubules and neurofilaments. Newly formed axons, small in diameter and containing many microtubules and neurofilaments, could been seen at 2 days after the operation among those that had degenerated. The regenerated axons were surrounded completely by Schwann cells. The Schwann cell processes became shorter at days and regenerated axons were situated in the space between Schwann cell and the basement membrane. Degenerated axons could no longer be seen 14 days after the operation, and regenerating axons increasing in diameter filled the nerve fibers. At 21-30 days, Schwann cell processes gradually extended to enclose regenerating axons, nerve fiber regeneration was complete 42-56 days after the operation. The manner of nerve regeneration was consistent with the results of a previous immunohistochemical study using anti GAP-43 (growth associated protein-43) antibody.