The nerve response after autotransplantation of the rabbit ear.

Neurohistologic investigations on 16 autotransplants of the rabbit ear ranging from 3 weeks to 18 months after replantation are described. This study investigated degeneration and regeneration of the adrenergic nerves of the vascular system and the afferent endings in hairy skin. Histochemical techniques, including hematoxylin-eosin staining by cholinesterase and glyoxylic acid fluorescence, and impregnation techniques with silver and osmium-zinc iodide were used. Central nerve reinnervation was started as early as 3 weeks after autotransplantation and usually was completed after 8 weeks. Spotty small areas of incomplete reinnervation could be found in the skin adnexa (hairs) even after 18 months. After transplantation the regeneration nerves were not attached to the vascular wall and were not incorporated in the Schwann cells of the distal parts of the transected and repaired vessels. The newly formed adrenergic nerve plexus was less dense than the normal one. Areas of patchy reinnervation and denervation were observed in peripheral vessels after 18 months. The defects in the restoration of the adrenergic vascular plexus similar to insufficient afferent reinnervation of skin and vessels may be responsible for the cold intolerance seen clinically and experimentally.