Peripheral nerve autografts to the injured spinal cord of the rat: an experimental model for the study of spinal cord regeneration.

Regenerated central axons have been shown experimentally to penetrate in peripheral nerve segments transplanted into the spinal cord (SC). However, if the nerves are transplanted between the stumps of the transected SC regeneration is impaired by local cavitation and scarring. Our experiment was designed to study whether nerve grafts bridging a severe transverse SC lesion might provide to central regenerating axons a pathway to by-pass the lesion. To this purpose, 2 segments of autologous peripheral nerves were inserted through small dural openings into dorsal longitudinal myelotomies rostral and caudal to a transverse SC lesion in rats. Eighteen weeks after transplantation a large number of well myelinated fibres filled the grafted nerves. Only a few of these fibres, however, could be followed into the SC; they were located in the outer layers of the dorsal white matter. The problems regarding the origin and destination of these fibres are discussed.