Degeneration and Regeneration Processes in Experimental Facial Nerve Paralysis

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Abstract
Facial nerve paralysis was provoked by compression of its extratemporal portion in rabbits, and the degeneration and regeneration of the nerve fibers was studied ultrastructurally. The compression was removed to study the regenerative process in 1 group of animals. Axonal and myelin degeneration were the 1st events seen as a collagen tissue proliferation from the endoneurium and perineurium. Ultimately, all the nerve was transformed into fibrous tissue. The myelin was disintegrated by Schwann''s cells without any macrophagic activiity. The regeneration process begins by the axons that are orientated towards Bungner''s bands of remnants of the Schwann''s cells, in which new myelin sheath appears. Schwann''s cells play an important role in both the degeneration and the regeneration process. The final aspect of the regnerated fibers is similar to normal, but they contain more collagen tissue, thinner myelin sheaths and a greater proportion of unmyelinated fibers.