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Schmidt-Lanterman incisures
Diagram of longitudinal sections of medullated nerve fibers. (Incisure labeled at upper left.)
Gray's	subject #183 727

In the peripheral nervous system (PNS) axons can be either myelinated or unmyelinated. Myelination means that the axon is insulated by surrounding layers of fatty membrane (myelin) produced by Schwann cells. These layers are continuous (like rolling up rope), but, due to the way they are formed, they often include small amounts of Schwann cell cytoplasm not displaced to the periphery during Schwann cell formation of the myelin. These are the so called Schmidt-Lanterman cleft (a.k.a. Schmidt-Lanterman incisures,clefts of Schmidt-Lanterman, segments of Lanterman, medullary segments), which subdivide the myelinated axon into irregular portions. They are histological evidence of the small amount of cytoplasm that remains in the inner layer of the myelin sheath created by Schwann cells wrapping tightly around a nerve.

[edit] External links

• Schmidt-Lanterman+incisures at eMedicine Dictionary
• Histology at BU 22801loa
• Slide at umdnj.edu

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