P0 immunostaining showed a comparable P0 immunoreactivity in the sciatic nerve of 6-w-old control mice, PERK cKO mice, Sel1L cKO mice, and Double cKO mice. E-H. Toluidine blue staining showed a comparable degree of myelination in the sciatic nerve of 6-w-old control mice, PERK cKO mice, Sel1L cKO mice, and Double cKO mice. I-O. EM analysis showed that the percentage of myelinated axons and the thickness of myelin were comparable in the sciatic nerve of 6-w-old control mice, PERK cKO mice, Sel1L cKO mice, and Double cKO mice. Scale bars: A-H, 20 μm; I-L, 5 μm. N = 4 animals. Statistical analyses were done with a 1-way ANOVA with a Tukeys posttest. Error bars represent SD, n.s. not significant.