Fig. 3.

Injury location relative to a bifurcation point impacts the degenerative and regenerative responses of axons. A) Main axon injury leads to the elimination of both branches followed by a regenerative response as detected by in vivo imaging. B, C) Ascending (B) or descending (C) axon injury close to the branch site leads to near complete elimination of one branch by both retrograde and anterograde degeneration, leading to the preservation of the spared branch but no detectable regenerative response from the injured branch as assessed by in vivo imaging. In (A–C), the bottom panel, adapted from (Lorenzana et al., 2015), shows an image acquired by in vivo imaging that illustrates the typical outcome for each injury location five days after injury. Scale bar = 100 μm.