Figure 1

Schematic illustration of the adult rat models of spinal cord injury used in this study. (a) Dorsal view of rat brain and spinal cord. Dorsal column white matter on the right side was transected (shaded area) at the C1/C2 spinal level, and the ability of either BDA-labeled endogenous axons or axons from microtransplanted GFP-expressing adult sensory neurons (DRGs) to cross injuries bridged with GDAs or GRPs was assayed. (b) Horizontal and (c) sagittal views of the dorsal column white-matter pathways at the C1/C2 cervical vertebrae of the spinal cord. (b) Injections of GDAs or GRPs (black diamonds) suspended in medium were made directly into the centers of the injury sites as well as their rostral and caudal margins in the cervical spinal cord. (c) A discrete population of endogenous ascending axons within the cuneate and gracile white-matter pathways of dorsal columns was labeled by BDA injection at the C4/C5 spinal level (5 mm caudal to the injury site, shaded). Alternatively, microtransplants of GFP⁺ DRGs were injected 500 μm caudal to the injury site. (d) The right-side dorsolateral funiculus white matter containing descending axons of the rubrospinal tract was transected at the C3/C4 spinal level and GDAs or GRPs were transplanted as described for dorsal column injuries. CC, central canal; Cf, cuneate fasciculus; CST, corticospinal tract; DF, dorsolateral funiculus; Gf, gracile fasciculus; GM, gray matter; RN, red nucleus; RST, rubrospinal tract; T1, level of the first thoracic vertebra.