FIG. 1.

Time line and schematic of injury, grafting, and exercise. (A) Time line of experiments showing acute PNGs placed at the time of SCI and chronic PNGs placed 6 weeks post-SCI. Exercise begins either acutely 5 days after initial SCI or with a delay at 5 weeks post-SCI, and it continues until the time of sacrifice. Animals are euthanized at 6 weeks post-SCI in acute PNG experiments or 12 weeks post-SCI in chronic PNG experiments. TB retrograde tracer is applied to distal ends of PNGs 5 days before euthanasia in all experiments. The group colors correspond to the colored bars in Figure 2. (B) Schematic showing initial SCI, apposition of aPNG to caudal lesion boundary and dPNG to rostral lesion boundary, and TB labeling of distal ends of PNGs in order to retrogradely label cell bodies of neurons extending axons into the grafts. aPNG, ascending PNG; dPNG, descending PNG; PNG, peripheral nerve graft; SCI, T12 spinal cord transection injury; TB, True Blue retrograde tracer.