Abstract
In previous studies, we have examined the substrate preferences of peripheral nervous system (PNS) axons elongating within a 15-mm gap in the rat sciatic nerve. Gaps were bridged with tubes filled with one of several porous collagen-glycosaminoglycan (GAG) copolymers. In this study, we have attempted to determine if this method for PNS regeneration can be used to study regeneration of axons in the central nervous system (CNS). A 5-mm gap was created in the midthoracic spinal cord of adult rats. Animals were divided into groups in which the gap was bridged with a collagen tube filled with one of two experimental collagen-GAG copolymers or bridged with an unfilled collagen tube. Lesions that were not bridged by a tubular device were included as controls. Rats were sacrificed at 30 days, and spinal cords, including the lesion site, were removed and studied histologically. Large numbers of myelinated axons were observed regrowing within the gap in animals of all groups. The presence of collagen tubes modified the organization and orientation of the fibrous component of reparative tissue and the migration pattern of astrocytes in the wound site. The results suggest that entubulation of the transected spinal cord is a useful technique for studying the substrate preferences of regenerating CNS axons.
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