Myelin

Structure of a typical neuron

Myelin sheath

Myelin is a dielectric (electrically insulating) material that forms a layer, the myelin sheath, usually around only the axon of a neuron. It is essential for the proper functioning of the nervous system. It is an outgrowth of a type of glial cell. The production of the myelin sheath is called myelination. In humans, myelination begins in the 14th week of fetal development, although little myelin exists in the brain at the time of birth. During infancy, myelination occurs quickly and continues through the adolescent stages of life.

Myelination

Definition: Myelination is the process by which a fatty layer, called myelin, accumulates around nerve cells (neurons). Myelin particularly forms around the long shaft, or axon, of neurons. Myelination enables nerve cells to transmit information faster and allows for more complex brain processes. Thus, the process is vitally important to healthy central nervous system functioning.

Myelination begins in infancy and continues into adulthood.  

Axon

Axon Definition: The hairlike extension of a nerve cell (neuron) that carries a message to the next nerve cell. The axon is covered with myelin.

In multiple sclerosis (MS), the myelin is damaged or destroyed by the immune system (demyelination), leaving a lesion, which slows the speed in which the axon transmits information. In aggressive or progressive forms of MS, the axon itself may be damaged or destroyed.

Link: http://en.wikipedia.org/wiki/Myelin

Link: http://tweenparenting.about.com/od/physicalemotionalgrowth/a/Definition-of-Myelination.htm

Link: http://ms.about.com/od/glossary/g/axon.htm

More Links:

American

http://www.nationalmssociety.org/What-is-MS/Definition-of-MS/Myelin

Myelin Repair Foundation

http://www.myelinrepair.org/

The Myelin Project  

http://www.myelin.org/

Multiple Sclerosis Foundation

http://www.msfocus.org/msf-publications.aspx
MSF videos
https://www.youtube.com/watch?v=MZg-AG4ZWxA
MSF on Twitter
https://twitter.com/MS_Focus