One of the major reasons for progressive multiple sclerosis is the progression of cell death in the myelin sheath which protects the nerve cells. This is an image from a scanning electron microscope showing the nerves and the protective covering of the myelin sheath. Electrically it's the myelin that insulates the nerve impulse and assures the electric message goes to the intended nerve cell target.
Myelin Sheath Protects Nerve Cells
Image compliments of: https://plus.google.com/u/0/108871877301789098084/posts/L4tdVqaUiuR?cfem=1