The axons are intermittently wrapped in a fatty substance called myelin.

轴突的某些位置可有髓鞘在外包绕。

Neural fibers are wrapped in a fatty substance called myelin.

神经纤维包裹在一种叫做髓磷脂的脂肪物质中。

Usually that size difference comes from a fatty substance called myelin that speeds up the conduction of electric signals.

通常这种大小差异来自一种叫做髓磷脂的脂肪物质，它可以加速电信号的传导。

Transverse means extending completely across something, in this case, it refers to going across the spinal cord, and myelitis means inflammation of myelin, which is the fatty substance surrounding nerves.

“横贯性 transverse”代表影响整个平面，这里特指脊髓平面；“脊髓炎 myelitis”代表脊神经髓鞘的炎症；髓鞘是包裹在神经纤维外面的一层脂质。