Electrophysiological and horseradish peroxidase-tracing studies of nerve regeneration through alginate-filled gap in adult rat spinal cord.

The spinal cord segments at T(9-10) were totally excised and the resulting gap was filled by implantation of alginate sponge in adult rats. A horseradish peroxidase-tracing study at 21 weeks after operation showed that numerous ascending and many but less numerous descending regenerating fibres traversed the alginate-filled gap, and that after re-entering the distal stump of the transected spinal cord, they extended randomly over a long distance away from the gap. Intracellular electrophysiological recording at the same postoperative time showed that both ascending and descending regenerating axons formed functional synapses with host neurons located beyond the gap. These findings suggest that alginate could be a promising material for the support of regenerating axons in the spinal cord.