Figure 4.

A. Thy1-CFP(23)/S100-GFP mice combine the SC and terminal axon characteristics seen in single transgenic mice. Quantitative assessment, however, is exclusively performed on the single transgenic mice to reduce the interrater variability that occurs with double transgenic mice. Specifically, CFP-labeled axons are not as bright as YFP axons and hence more difficult to accurately count. B. To demonstrate cellularity at the motor endplate while GFP signals are changing, SC nuclei are also labeled with DAPI. Prior to injury, many of the cells associated with motor endplates are characterized by blue-green colabeling. C. One week after crush injury, there are very few DAPI-labeled cells that are colabeled with GFP. D. Two weeks later, motor endplates are densely populated with DAPI-labeled nuclei and colabeling with an attenuated GFP signal is noted by some TSCs. This suggests that TSCs are present and viable, but have regressed to a more immature phenotype that expresses S100 less intensely. E. Proximal to these TSCs, robust proliferation of peripheral SCs is noted along the paths of regenerating terminal axons two weeks following crush injury. F. Four weeks after injury, TSCs colocalizing GFP and DAPI show restoration of the mature S100-expressing SC phenotype.