Fig. 3: Acute axonal degeneration in the absence of microglia-node interaction.

a An in vivo spinal cord image shows significantly decreased microglial density after 3-week treatment of PLX3397 (290 mg/kg). Orange, YFP labeled axons; Green, GFP labeled microglia. Scale bar, 50 μm. b Statistics of microglial density (Average cell number per field of view (300 μm*300 μm*45 μm)) before (n = 7) and after 3-week treatment of PLX3397 (n = 6). Data are presented as mean ± standard deviation (SD). Unpaired two-tailed t-test: ****P < 0.0001. In the absence of microglial contacts with nodes, axonal response to laser axotomy performed proximal to a normal NR (c), on a daughter branch of a secondary branch point (BP) (d) and on both daughter branches of a secondary BP (e). Time post injury is presented as hr:min. Scale bar, 20 μm. Insets, overlay of SRS (blue) and YFP image (orange). White arrowheads indicate the position of the targeted normal nodes and branching nodes. Scale bar, 10 μm. f Distance between proximal ends and NR of the injured axons at 0 and 24 hpi. A total of 12 axons from 6 mice were recorded. g Plot of degeneration length against the distance between the axotomy site and NR at 4–6 hpi. Data points above the dashed line represent the incidence of nodal breach. Axonal degeneration data shown in Fig. 2d was reprocessed as the ‘Ctrl’ datasets here. h Distance between proximal ends and secondary BPs of the injured axons at 0 and 24 hpi. A total of 6 axons from 5 mice were recorded. Source data are provided as a Source Data file.