Figure 12.

YFP⁺ neurons expressing phospho-c-Jun at later time points post-injury exhibit morphological evidence of continued axon regeneration and/or plasticity. A, Representative image of normal YFP⁺ axonal morphology (arrowheads) present in 28 d sham-injured animals. B–M, Representative images of YFP⁺/phospho-c-Jun⁺ neurons at 14 d (B–I) and 28 d (J–M) post-injury. Detailed axonal morphology of YFP⁺ neurons is shown in B, F, and J. The same YFP⁺ neurons (C, G, K) all expressed phospho-c-Jun (p-c-Jun) (D, H, L, arrowheads). These YFP⁺/phospho-c-Jun⁺ neurons at 14 and 28 d consistently maintained axons that were no longer swollen nor displayed overt pathological alteration. Rather, they now displayed long, thin axonal profiles decorated by several small dilations along their length (B, F, J, arrowheads). These were capped by torpedo-shaped swellings (B, F, J, arrows). Reconstructed three-dimensional images depicting the terminal swellings for each neuron are shown in E, I, M. Scale bars: A, B, J, 50 μm; F, 25 μm.