Myelin a protective substance is beginning to coat the spinal column.

髓磷脂是一种防护物质，它开始覆盖在脊柱的表面。

youdao

Myelin, a protective substance, is beginning to coat the spinal column.

髓磷脂是一种防护物质，它开始覆盖在脊柱的表面。

youdao

Myelin, a protective substance, is beginning to coat the spinal column.

髓磷脂是一种防护物质，它开始覆盖在脊柱的表面。

youdao