myeliniserde

Myeliniserde refers to nerve fibers that have been ensheathed with myelin, a lipid-rich layer that surrounds axons. In the central nervous system (CNS), myelin is formed by oligodendrocytes; in the peripheral nervous system (PNS), by Schwann cells. A myelinated axon contains repeated segments of myelin (internodes) separated by gaps known as nodes of Ranvier, where the axonal membrane remains exposed.

Functionally, the myelin sheath increases the conduction velocity of electrical signals and improves energy efficiency. By insulating the axon, myelin enables saltatory conduction, allowing action potentials to jump from node to node. This reduces membrane capacitance and lowers the amount of ion pumping required to restore ion gradients after firing, conserving cellular energy.

Structurally, internodes vary in length and are wrapped by multiple layers of glial cell membrane. The myelin sheath is rich in lipids, including cholesterol and sphingolipids. At the nodes of Ranvier, clusters of voltage-gated sodium channels facilitate rapid depolarization and signal propagation.

Developmentally, myelination begins in late prenatal life and continues into adolescence, with regional and species differences. Axon caliber and neural activity influence the timing and extent of myelination. Myelination can beIncomplete or reversed in certain injury or disease states, though remyelination is possible in many contexts, particularly in the PNS.

Clinical relevance is significant: demyelinating diseases disrupt nerve conduction and impair function. Examples include multiple sclerosis (CNS) and Guillain-Barré syndrome (PNS); genetic leukodystrophies affect myelin formation. Diagnosis and research often utilize imaging methods (e.g., MRI metrics of myelin) and histological markers such as Luxol fast blue staining or myelin-associated proteins (MBP, PLP).