Fig. 1: Microglial physical contact with Nodes of Ranvier (NR) in the normal spinal cord.
From: In vivo imaging in mouse spinal cord reveals that microglia prevent degeneration of injured axons
a Schematic of in vivo imaging of mouse spinal cord through an optically cleared intervertebral window with ligamentum flavum (IWLF). b Morphologic components of a myelinated axon. M, myelin sheath; IN, internode; JP, juxtaparanode; P, paranode; N, node. In vivo imaging of multiple NRs in mouse spinal cord. White arrowheads indicate the location of the same numbered NR in (c) and (d). Orange, YFP-labeled axons; blue, stimulated Raman scattering (SRS) image of myelin sheath taken at 2863.5 cm−1. e Three-hour time-lapse imaging of the nodes 1-3 shown in (b, c) together with surrounding microglia (green), showing dynamic microglia-node interaction. Red arrowheads indicate the occurrence of microglia-node contact while blue arrowheads indicate no microglial contact at the target nodes. Purple arrowheads show two microglial cells which contact the same node (Node 1) at the same time. Time is presented as hr: min. f Heatmap showing microglia-node contact events during three-hour time-lapse imaging. Each row represents a NR. Totally 67 nodes from 7 mice were recorded. The first three rows represent the data of three nodes shown in (b, c, e). g The statistics of the two forms of microglia-node contact shown in (f). h Diagram showing the definition of microglial primary and secondary processes. i The statistics of nodal contacts performed by different microglial components in the case of intermittent (top) and constant contact (bottom). j Percentage of nodes with microglial contact over time. The gray area indicates a small region where locates all the data points. Scale bars, 20 μm in (c) and (e), 10 μm in (d). Figures (a, b, h) created using BioRender (https://biorender.com/). Source data are provided as a Source Data file.
