Myelin morphology and quantification after interleukin 17 (IL-17) treatment. (A-E) For myelin quantification, mouse dorsal root ganglia (DRG) co-cultures were exposed to IL-17 for 21 days at the indicated concentrations and subsequently stained, using Sudan black dye. Images show myelin layer (α) and Schwann cell body (β) are separated from the next internode by Ranvier’s node (γ) and neuronal cell bodies (δ). In analysis of three independent experiments, quantification revealed a myelin ratio (internodes to neurons) reduction to 66% for 0.5 ng/mL IL-17 (**P = <0.01), to 55% for 5 ng/mL IL-17 (**P = <0.01), and to 42% for 50 ng/mL IL-17 (**P = <0.01), each compared with control stimulations. (F) Internodal distances after exposure to IL-17 revealed a significant decrease with 5 ng/mL IL-17 (*P = <0.05) and 50 ng/mL IL-17 (*P = <0.05). Analysis of variances between the independent experiments revealed no significant difference. (G) Myelin quantification of Sudan-stained DRG co-cultures after treatment with IL-17, an IL-17-neutralizing antibody (αIL-17ab), and co-stimulation of three independent experiments, respectively. The myelin-inhibitory effect of IL-17 was reduced by 81% after supplementation with αIL-17ab. Myelination was restored to the base level, similar to treatment with the antibody alone.