Regeneration in cellular and acellular autografts in the peripheral nervous system.

The regeneration that occurs in cellular autografts of sciatic nerve has been compared with that seen in acellular models prepared either by cycles of alternating freezing and thawing, or by detergent-extraction. The responses to either fresh or pre-degenerate grafts (cellular and acellular) have been examined electron microscopically. It was found that whereas neurites grew into a fresh autograft and rapidly re-established functional relationships with vital Schwann cells lying in bands of Büngner within the graft, penetration of acellular grafts was less efficient. Many basal lamina tubes in the acellular grafts remained either empty or filled with debris-laden macrophages for the first 2 weeks after suture, although subsequently reinnervation did occur. The roles of Schwann cells, macrophages and basal laminae during reinnervation are discussed.