myelinikerroksia

Myelinikerroksia are the concentric layers of myelin sheath that envelop the axons of neurons in the central and peripheral nervous systems. The sheath is produced by oligodendrocytes in the CNS and Schwann cells in the PNS. Each myelin layer is composed mainly of phospholipids and a small amount of protein, with myelin basic protein (MBP), proteolipid protein (PLP), and gliomedin being predominant components. The lipid bilayers are tightly packed, creating a high‑density membrane that insulates the axon and significantly increases the speed of action potential propagation via saltatory conduction.

The layers are arranged in a spiral wound around the axon. In oligodendrocytes, one cell can myelinate segments of multiple axons, while a single Schwann cell typically myelinates a single axonal segment. The number of layers varies; in mature myelin sheaths, there may be dozens of lamellae. The thickness of the sheath, reflected in the g-ratio (axon diameter/total fiber diameter), is optimized for efficient conduction.

Disruption or loss of myelin layers underlies demyelinating disorders such as multiple sclerosis, Guillain‑Barre syndrome, and Charcot‑Marie‑Tooth disease. In these conditions, inflammation, autoimmune attacks, or genetic defects impair the formation or maintenance of the myelin layers, resulting in slowed or blocked nerve conduction. Therapies aim to reduce demyelination, promote remyelination, and restore functional layers.

Research continues to elucidate the molecular mechanisms governing layer assembly, turnover, and repair. Understanding myelinikerroksia is essential for developing targeted strategies to treat demyelinating diseases and improve neural regeneration.