Figure 4.
Axon-derived NRG1 is required for remyelination after nerve injury in the adult. A, At 8 weeks after sciatic nerve crush, control (vehicle-treated SLICK-A Cre; NRG-1fl/fl) animals demonstrated effective remyelination of YFP-expressing axons. B–D, In contrast, YFP-positive axons from conditional NRG1 mutant (tamoxifen-treated SLICK-A Cre; NRG-1fl/fl) mice either had a significantly thinner myelin sheath (B) or completely failed to elaborate a myelin sheath (C; quantified in D, G-ratio plot; p < 0.001, Kolmogorov–Smirnov test). Note in B a neighboring axon that is YFP negative is normally myelinated. E, Graphic plot displaying numbers of unmyelinated YFP-positive axons (n = 4 animals per group). Vh., Vehicle; Tx., tamoxifen. Scale bar, 500 nm.