Myelin staining of brainstem from IGF-I KO and littermate control mice during development. Brains of IGF-I KO mice (E–H) and their littermate controls (A–D) were perfusion fixed with 4% paraformaldehyde, sectioned, and stained using the LFB-PAS method. Sections from mice at 1 week of age are shown in A andE, 2 weeks are shown in B andF, 3 weeks are shown in C andG, and 10 weeks are shown in D andH. Scale bar, 50 μm.