The nodes of Ranvier
- 20 November 1952
- journal article
- Published by The Royal Society in Proceedings of the Royal Society of London. B. Biological Sciences
- Vol. 140 (900), 301-320
- https://doi.org/10.1098/rspb.1952.0063
Abstract
At a node of Ranvier the axon is reduced in diameter; on the largest mammalian fibres the reduction is to less than half of the internodal diameter. The axoplasm at the node has optical properties different from the internodal axoplasm, but there is no visible transverse boundary across it. The length of the portion of axon left uncovered at the node is less than 0·5μ in the largest mammalian fibres; it is somewhat greater on the smaller fibres. The area of the cylinder of axon membrane exposed at the node increases only slightly with increasing fibre diameter. This area is 4μ2, and the area of the surface of the narrow portion of the axon is about 90μ2, in the largest mammalian fibres. The exposed portion of the axon is probably not covered by Schwann cell protoplasm, but is surrounded by a 'cementing disk’ composed of scleroprotein material, continuous with the neurilemma (inner endoneurium). This disk has a radial thickness of 5μ in the largest mammalian fibres. Outside this disk is a perinodal space with no stainable contents, bounded externally by the collagenous outer endoneurium (sheath of Key & Retzius). Methylene blue and silver nitrate entering the fibres at the node stain the whole narrow region, suggesting that this, rather than the myelin-free area, may constitute the effective nodal membrane. Periodic interruptions of the myelin occur along fibres of the spinal cord of rabbits, probably on all fibres. On central fibres of 3 to 15μ in diameter the internodal lengths vary from 300 to 1700μ. As in peripheral nerves internodal length increases with growth; in smaller rabbits this length is less for any given fibre diameter than in larger animals. In new -born rabbits the smallest fibres have internodes as short as 200μ.Keywords
This publication has 11 references indexed in Scilit:
- The uptake and loss of phosphate by frog muscleBiochemical Journal, 1951
- The electron microscopy of myelinated nerveBiochimica et Biophysica Acta, 1950
- Distribution of nodes and incisures in normal and regenerated nerve fibersThe Anatomical Record, 1947
- THE FUNCTIONAL REPAIR OF NERVOUS TISSUEPhysiological Reviews, 1942
- The Discovery of the Cell of Schwann in 1839The Quarterly Review of Biology, 1939
- THE ULTRASTRUCTURE OF THE NERVE AXON SHEATHBiological Reviews, 1939
- Electrical Signs of Nervous ActivityPublished by University of Pennsylvania Press ,1937
- THE AXIS-CYLINDER AS A PATHWAY FOR DYES AND SALTS IN SOLUTION, WITH OBSERVATIONS ON THE NODE OF RANVIER IN THE RABBITBrain, 1937
- Clinical MemorandaBMJ, 1889
- Samuel WrightNotes and Queries, 1872