Figure 2.

Quantification of numbers of regenerating BDA⁺ axons in GDA-transplanted versus control dorsal column white matter at 8 days after injury and transplantation. BDA-labeled axons were counted in every third sagittally oriented section within the lesion center and at points 0.5 mm, 1.5 mm, and 5 mm rostral to the injury site, up to and including the dorsal column nuclei (DCN). Note that 61% of BDA⁺ axons had reached the centers of GDA-transplanted lesions and 39% to 0.5 mm beyond injury sites, compared with just 4% (lesion center) and 3.8% (0.5 mm rostral) present in controls. The steady decline in numbers of BDA⁺ axons within rostral white matter indicates a staggered front of maximum axon growth beyond sites of injury in GDA-transplanted groups at this time point. Note the total absence of axons at 5.0 mm rostral and in dorsal column nuclei in controls. Counts of BDA⁺ axons labeled in all adjacent sagittally oriented sections in representative GDA-treated and control lesioned cords revealed totals of 372 and 330 axons, respectively, at 0.5 mm caudal to the injury site. Increases in numbers of BDA⁺ axons in GDA-treated animals compared with controls were statistically significant (p < 0.01) in all rostral spinal cord regions. Error bars indicate ± 1 standard deviation.