FIG. 3.

Corticospinal tract (CST) tracing. Biotinylated-dextran amine (BDA)-traced CST axons (B–D, K, and O) approach the lesion/transplant but do not extend into or around dissociated predegenerated nerve (dPDN) (A) or Schwann cell (J) transplants. Dashed ovals demarcate similar regions in adjacent sections with green fluorescent protein-labeled transplants (A and J) and BDA traced axons with cresyl violet counterstained nuclei (B and K). For a dPDN transplant case (A–I), CST axons in three adjacent sections separated by 160 μm are depicted (B–D). Single sections through the dorsal CST are shown for the SC (K) and SCI (O) groups. E, F, L, and P are enlargements of the boxed regions in D, K, and O, of the main termination of the dorsal CST rostral to the injury/transplant. Fine CST axons were detected and terminated in retraction bulbs in all cases (dPDN, G–I; SCs, M and N; SCI, Q and R). G–I, M, N, Q, and R are enlargements of the boxed regions in F, L, and P (scale bars=500 μm in A–D, J, K, and O;=50 μm in E, F, L, and P;=10 μm in G–I, M, N, and P–R; green, GFP-labeled transplanted cells; brown, BDA-traced CST axons; blue, cresyl violet counterstained nuclei).