Another example of a synthesis reaction is the formation of sodium chloride (table salt). Because of the very high reactivities of sodium metal and chlorine gas, this reaction releases a tremendous amount of heat and light energy.
Schwann cells make myelin in the peripheral nervous system (PNS: nerves) and oligodendrocytes in the central nervous system (CNS: brain and spinal cord). In the PNS, one Schwann cell forms a single myelin sheath (Figure 1A).
Myelination consists of multiple layers of the cell membrane of either oligodendrocytes or Schwann cells (neurolemmocytes) wrapped around the axons of neurons. The cell membrane wrapping is called myelin. A number of glial cells are necessary to form the myelination along the length of an axon.