Figure 2: Intravital imaging of oligodendrocytes and myelin.

a) Fluorescence labeling and in vivo imaging of single oligodendrocyte lineage cells in the mouse cortex. Isolated NG2 glia or oligodendrocytes can be visualized after a low dose injection of tamoxifen to induce cre recombination in single cells in Cspg4-creER transgenic mice. Membrane tethered GFP allows visualization of NG2 glia processes or myelin internodes. Arrowheads indicate cell soma b) The small molecule fluorescent dye sulforhodamine 101 (SR101) allows in vivo visualization of astrocyte and oligodendrocyte gap junction coupling. Astrocytes initially take up the dye which then diffuses to coupled myelinating oligodendrocytes. Arrowheads indicate oligodendrocyte cell soma. c) Label-free spectral confocal reflectance (SCoRe) microscopy in the live mouse cortex. The reflection of multiple wavelengths (left image, 448 nm, 552 nm, and 638 nm laser wavelengths used) is combined to visualize myelination (middle image) which maps precisely with membrane localized EGFP in Cnp-mEGFP transgenic mice (right image). Arrowheads indicate oligodendrocyte cell soma. d) Nodes of Ranvier (arrow) can be visualized in vivo using SCoRe and/or mEGFP labeling.