More specifically, MS destroys oligodendrocytes, the cells responsible for creating and maintaining a fatty layerknown as the myelin sheathwhich helps the neurons carry electrical signals (action potentials).[4] MS results in a thinning or complete loss of myelin and, as the disease advances, the cutting (transection) of the neuron's axons. When the myelin is lost, a neuron can no longer effectively conduct electrical signals.[4] A repair process, called remyelination, takes place in early phases of the disease, but the oligodendrocytes cannot completely rebuild the cell's myelin sheath.[26] Repeated attacks lead to successively fewer effective remyelinations, until a scar-like plaque is built up around the damaged axons.[26] Different lesion patterns have been described.[27]