Myelin is made of fat and protein, and it helps to speed transmission of a nerve impulse down a long axon. Depending upon the type of neuron, axons can be covered with a thin layer of myelin sheath, like an insulated electrical wire. This long, cablelike projection of the cell carries the electrochemical message (nerve impulse or action potential) along the length of the cell.
This main part has all of the necessary components of the cell, such as the nucleus (which contains DNA), endoplasmic reticulum and ribosomes (for building proteins) and mitochondria (for making energy).
