Fig. 7: CST axons that regenerate through the PLG bridge are synaptically connected.

a Horizontal section showing PRV labeling (green) in the control group; inset b shows that PRV fibers were not observed in the SCI control lesion. c Horizontal section showing PRV labeling in the PLG group. Higher magnification insets show PRV+ fibers caudal to the PLG bridge (d); PRV+ regenerated fibers inside PLG bridge channels (e–g); PRV+ fibers rostral to the PLG bridge (h). i Quantification of PRV labeling in the lesion site. Statistical analysis by unpaired Student’s t-tests one-tailed (*p < 0.044; n = 3 biological replicates/group; Mean ± SEM). j, k Representative image of PRV labeling in the contralateral motor cortex. j SCI control and k PLG bridge groups. l, m Quantification of total PRV-labeled CST cell bodies in the motor cortex. l contralateral motor context and m ipsilateral motor cortex. Statistical comparisons were conducted using one-way ANOVA, followed by Tukey post hoc tests (**P ≤ 0.01) and comparisons showing # are using unpaired t-tests two-tailed (#p ≤ 0.05, ##p ≤ 0.01; n = 3–5 biological replicates/group; Mean ± SEM). n STEM121+ cells (red) stained positive for PRV (GFP, green), suggest stable integration into host circuitry. o Representative image of STEM121+ processes (red) wraping around PRV fiber (green) suggests hNSC myelination of PRV-labeled host axon. Scale bars: a, c 500 μm; b 10 μm; d, h 100 μm; e, f 10 μm; g 5 μm; j, k 100 μm; n, o 10 μm.