Figure 1: Axons that swell following spinal contusion can break down or recover.

(a) Low-magnification confocal image showing the extent of damage 4-h p.i. in a fixed spinal cord whole-mount derived from a transgenic Thy1-YFP16 mouse (greyscale). Dying cells were labelled by incubation with ethidium homodimer (magenta) revealing the location of the contusion area (dashed circle). The approximate dimensions of the field of view obtained from in vivo time-lapse montages are shown by green scale bars. (b) Single frame (montaged maximum intensity projection) from a multiphoton in vivo time-lapse showing the range of axonal morphologies present after contusion including healthy appearing (pseudocoloured green), swollen (yellow) and broken (red). (c) Magnified details from in vivo time-lapse recordings showing typical changes in axonal morphology at the indicated times as min p.i. (‘pre’: before injury). Swollen axons can progress to a broken state (left panel); however, spontaneous recovery events are also observed (right panel; axons pseudocoloured as in b; Thy1-YFP16 line). (d) Graph showing the morphological changes of a large population of contused axons (194 axons, 4 Thy1-YFP16 mice). Scale bars in b,c, 20 μm.