Figure 3. Ablation of MRF causes severe demyelination. A, Electron microscopy analysis of the optic nerve at 8 weeks after 4OHT reveals substantial demyelination and other signs of myelin pathology, such as vacuolization (*) in the iCKO mice. B, At 8 weeks after 4OHT, the lateral white matter of the spinal cord contains more signs of active demyelination, including substantial vacuolization, delamination, and myelin debris. C, D, Higher-magnification images of a thinly myelinated (presumably remyelinated) axon in the optic nerve (C) and degrading myelin in the spinal cord (D). E, At 8 months after 4OHT, both the optic nerve and spinal cord of the iCKO mice show substantial remyelination as evidenced by numerous thinly myelinated axons. F, Quantification of the proportion of axons myelinated in the optic nerve and lateral white matter of the spinal cord of iCKO mice and controls at 8 weeks and 8 months after 4OHT administration. Data are means ± SEM. *p < 0.05, **p < 0.01. n = 3 animals per condition. Scale bars, 1 μm. G, H, g-ratios of individual axons as a function of axonal diameter in the spinal cord (G) and optic nerve (H) in controls and iCKOs at 8 months after 4OHT.