FIGURE 1.

In vivo imaging of oligodendrocytes. (A) Cranial windows were surgically implanted in adult Mobp-EGFP mice in which only oligodendrocytes express EGFP. (B) Orientation of oligodendrocytes from imaging surface to white matter. Oligodendrocytes in upper cortical layers myelinate horizontally aligned axons, while those in deeper cortical layers are aligned perpendicularly to pial surface. Standard imaging range of two-photon and three-photon microscopy highlighted with approximate gradients (Theer and Denk, 2006; Lecoq et al., 2019) (C) XY maximum projections of 100 μm thick volumes at indicated depths (0–100 μm, 100–200 μm, 200–300 μm, and 300–400 μm). Layer depths as estimated in somatosensory cortex (Narayanan et al., 2017). Oligodendrocyte density increases rapidly with depth, increasing the time needed for manual tracking. Scale bar: 50 μm.