The Myelin Sheath: Shape, Size, and Composition What exactly is myelin? Myelin is a concentrically laminated membrane structure surrounding an axon around which lamellae (or cellular protrusions ...

A long fibre (axon) which is insulated by a fatty (myelin) sheath. They are long so they can carry messages up and down the body. Tiny branches (dendrons) which branch further as dendrites at each ...