Demyelination and axonal damage were found in the peripheral nerves of symptomatic L31/CD4
mice. Myelin in the sciatic nerves was stained with FluoroMyelin. Representative illustrations from longitudinal (A-I) and cross (J-N) sections showed an intact myelin structures in wild type (A, E, J) and pre-symptomatic L31 mouse sciatic nerves (B, F, K), and a focal (C, H) or diffused, severely damaged myelin (D, G) in symptomatic L31 mice. In parallel with demyelination, the axonal damage evidenced by the loss of PGP9.5 staining was detected in symptomatic L31 mice (G, H, L, M, N). Some naked PGP9.5+ axonal fibers were found in the area where myelin disappeared or fragmented (G, H, L, M, N). I: Myelin labelling was found in a cell-shaped structure containing a DAPI+ nucleus, which suggests a macrophage with engulfed myelin fragments. Two naked axonal fibers were located nearby. ATF3 positive signals were found in the cell bodies of both DRG sensory neurons (O) and spinal cord ventral horn (VH) motor neurons (P). Scale bar: 50 μm.