myelin
noun [ U ] anatomy specialized uk/ˈmaɪə.lɪn/ us/ˈmaɪə.lɪn/
髓磷脂（含大量脂肪，特别是在脑神经周围形成保护层，保障脑神经有效发出信号）
a substance containing a lot of fat that forms a covering around nerves, especially those in the brain, protecting them and helping them to send signals effectively
The myelin sheath around the neuron is damaged. 神经元周围的髓鞘遭到破坏。