Sarm1 is required for Wallerian degeneration in mice in vivo. (A) Sciatic nerve distal to the injury site stained with Toludine blue. Time points and genotypes as indicated. (B) Ultrastructural analysis of Sarm+/− and Sarm−/− axons before or 14 days after axotomy. Higher magnification image (lower right) is shown in its entirety in fig. S4. my, myelin; nf, neurofilaments; m, mitochondrion. (C) Neuromuscular junction (NMJ) preservation at tibialis anterior muscles. red, AChR (postsynapse/muscle); green, NF-M/synpatophysin (presynapse). Arrows, motor end plates. (D) Immunoblot analysis of distal injured nerve segment. n = 4 mice at each time point and genotype.