Nerve demyelination. Animation showing white blood cells attacking the myelin sheath (yellow) that insulates nerve cells. This impairs the nerves ability to relay signals efficiently. This is an example of an autoimmune condition, where the body's immune system attacks healthy tissue. An example of an autoimmune disease that causes demyelination is multiple sclerosis (MS).HD master is flattened onto a black background, as seen in this preview. The original file has a transparent alpha channel and is available as the HD master of clip K003 3787.