Myelinet

The term “myelinet” does not correspond to a widely recognized biological term and may be a misspelling of myelin or myelination. The following article summarizes the concepts most commonly associated with that term: myelin, the myelin sheath, and the process of myelination that forms it.

Myelin is a lipid-rich sheath that surrounds axons in the central nervous system (CNS) and peripheral nervous system (PNS). It is produced by oligodendrocytes in the CNS and by Schwann cells in the PNS. By wrapping the axon with multiple membranous layers, myelin increases the speed of electrical impulse conduction along the nerve fiber through saltatory conduction and reduces the energy needed to propagate signals.

The myelin sheath is composed largely of lipids (about 70-85% of dry weight) and specific proteins. In the CNS, major proteins include myelin basic protein (MBP) and proteolipid protein (PLP). In the PNS, key proteins include myelin protein zero (P0) and peripheral myelin protein 22 (PMP22). Lipids such as cholesterol and sphingolipids contribute to the compact structure that insulates axons.

Myelination begins during development and continues after birth, often extending into adolescence for many brain regions. The process forms internodes—myelinated segments between nodes of Ranvier—separated by nodes where ion channels are concentrated, enabling rapid, saltatory conduction.

Clinical significance includes demyelinating conditions that disrupt nerve signaling. CNS demyelination occurs in diseases such as multiple sclerosis, while peripheral demyelination can arise in Guillain-Barré syndrome and CIDP. Myelin integrity is essential for efficient and coordinated neural communication.