Fig. 5

OPCs increase proliferation after SCI. (A) At 7 dpl, proliferating olig2:eGFP⁺/PCNA⁺ OPCs can be detected both in the parenchyma and the ventricle (overview/inset, yellow arrowheads). Images are maximum intensity projections of transverse sections. D, dorsal; V, ventral. In the overview images, a white asterisk indicates the central canal. Scale bars: 100 µm. (B) Stereological quantification of parenchymal olig2:eGFP⁺/PCNA⁺ cells 700 µm around the transection site shows a significant increase in proliferating OPCs at 7 dpl, compared to sham controls. Data are mean±s.e.m. Numbers in the plots indicate the number of experimental animals. ****P≤0.0001; **P≤0.01 (Kruskal–Wallis test followed by Dunn's multiple comparisons post-hoc test). Significance is shown compared to sham control. (C) Stereological quantification of parenchymal olig2:eGFP⁺/PCNA⁺ cells 700 µm around the transection site in sham controls shows that both non-reactive and reactive OPCs proliferate. (D) Stereological quantification of parenchymal olig2:eGFP⁺ cells 1400 µm around the transection site at 7 dpl shows no significant difference in the GFP+ cells along the RC axis (Kruskal–Wallis test followed by Dunn's multiple comparisons post-hoc test). (E) Schematic representation of OPCs becoming reactive immediately after lesion and proliferating. (F) Timeline of EdU labelling experiment to monitor generation of new OPCs. (G) Strategy to image and analyse OPC proliferation in whole-mount tissue after SCI and tissue clearance. (H) Optical section of whole-mount zebrafish spinal cord of transgenic Tg(olig2:eGFP) fish after CUBIC-based tissue clearance. At 14 dpl, the size of the ventricle is markedly increased (see also Fig. 4), while proliferation of both parenchymal and ventricular cells is upregulated. Scale bars: 100 µm. (I) Quantification of the percentage of olig2:eGFP⁺/EdU⁺ parenchymal OPCs 700 µm around the transection site after 3D-reconstruction in Imaris shows a significant increase in the percentage of newly generated OPCs at 14 dpl, compared to sham controls. Data are mean±s.e.m. Numbers in the plots indicate the number of experimental animals. ***P≤0.001 (Mann–Whitney test). Significance is shown compared to sham control.