Flexible ensheathment of axons enables myelination of complex CNS networks - PubMed
3 hours ago
- #neuroscience
- #oligodendrocytes
- #myelination
- Myelin sheaths by oligodendrocytes in the CNS are crucial for circuit function and neural health, with distribution varying across brain regions, neuron subtypes, and individual axons.
- Contrary to the previous belief of one sheath per oligodendrocyte process, flexible ensheathment allows processes to extend past axon branch points and nodes of Ranvier, forming chains of sheaths connected by thin cytoplasmic processes called paranodal bridges.
- In the cerebral cortex, paranodal bridges enable oligodendrocytes to myelinate highly branched axons, such as those of parvalbumin interneurons, expanding myelin territory and reducing the need for oligodendrocytes.
- Flexible ensheathment leads to the formation of myelin chains, but terminal sheaths in these chains are more vulnerable, degenerating more frequently in the aged brain and contributing disproportionately to myelin loss.