Membrane architecture of myelinated nerve fibres in the human dental pulp studied by freeze-fracturing.
The outer surface of the myelin sheath was well visualized in electron micrographs of replicas and the distribution of its cytoplasm-containing portions could be analysed. Numerous caveolae, probably representing the surface stomata of endo- or exocytotic vesicles were found on the plasmalemmal surface overlying organelle-rich cytoplasmic regions. Membrane specializations of the tight-junction type were found at the outer and inner mesaxons of the myelin sheath as well as at the Ranvier node and Schmidt-Lanterman incisures. Presuming that so-called leakiness is related to the junctional morphology, these junctions would be classified as moderately leaky. The morphological features of the Schwann-cell nuclear envelope were essentially as described for other mammalian cells.
D000293:Adolescent; D000328:Adult; D002462:Cell Membrane / Q000648:ultrastructure; D003782:Dental Pulp / Q000294:innervation* / Q000648:ultrastructure; D005614:Freeze Fracturing; D006801:Humans; D007365:Intercellular Junctions / Q000648:ultrastructure; D007425:Intracellular Membranes / Q000648:ultrastructure; D008854:Microscopy, Electron; D009186:Myelin Sheath / Q000648:ultrastructure; D009413:Nerve Fibers, Myelinated / Q000648:ultrastructure*; D009685:Nuclear Envelope / Q000648:ultrastructure