Figure 7

Failure of axons to regenerate across GDA^CNTF or GRP transplanted dorsal column injuries. (a) Biotinylated dextran amine (BDA)-labeled endogenous, ascending dorsal column axons (green) fail to cross GDA^CNTF-transplanted injury sites and instead form dystrophic endings within caudal injury margins. While a few axons sprout towards the injury center, BDA⁺ axons are rarely detected beyond the injury/transplantation site at 8 days post-injury/transplantation. Scale bar 200 μm. (b) In contrast, transplanted GDAs^BMP support extensive axon growth across dorsal column injuries at 8 days after injury/transplantation. Scale bar 200 μm. (c) Quantification of numbers of regenerating BDA⁺ axons in GDA- or GRP-transplanted dorsal column white matter at 8 days after injury and transplantation. BDA-labeled axons were counted in every third sagittally oriented section within the injury center and at points 0.5 mm, 1.5 mm and 5 mm rostral to the injury site and within the dorsal column nuclei (DCN). Note that 55% of BDA⁺ axons reached the centers of GDA^BMP-transplanted injuries, and 36% to 0.5 mm beyond the injury site. After GDA^CNTF or GRP transplantation, however, only 7% and 5.3% of BDA⁺ axons, respectively, were observed within injury centers, with only 4.6% and 4.2% of the axons observed at 0.5 mm beyond the injury site. No BDA⁺ axons were detected beyond 1.5 mm rostral to the injury site in GDA^CNTF- or GRP-transplanted spinal cords. Error bars represent 1 SD.