Abstract
The lengths of internodes on peripheral and central stretches of the same ventral motoneuron axons were measured in 6 day rats. The former were more than twice as long as the latter. The distribution of peripheral internodal lengths was broader, and was shifted to the right, relative to that of central internodes. Short internodes were present centrally and peripherally throughout the early period of rapid myelination occurring immediately after birth. All such internodes appeared normal centrally, as did a proportion found peripherally. Some peripheral examples appeared to be degenerating. Evidence is presented suggesting that some short internodes, both peripherally and centrally, increase in length to achieve a normal appearance. Many central stretches of central motoneuron axons which were myelinated at some levels, at other levels possessed unmyelinated segments covered by numberous short glial processes. Such bare stretches commonly occurred immediately deep to the cord surface. The lengths of the unmyelinated stretches decreased as age advanced, perhpas due to the extension of adjacent myelinated segments along them.
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- BODIAN D. A note on nodes of Ranvier in the central nervous system. J Comp Neurol. 1951 Jun;94(3):475–483. doi: 10.1002/cne.900940309. [DOI] [PubMed] [Google Scholar]
- Berthold C. H., Skoglund S. Postnatal development of feline paranodal myelin-sheath segments. I. Light microscopy. Acta Soc Med Ups. 1968;73(3-4):113–126. [PubMed] [Google Scholar]
- Berthold C. H., Skoglund S. Postnatal development of feline paranodal myelin-sheath segments. II. Electron microscopy. Acta Soc Med Ups. 1968;73(3-4):127–144. [PubMed] [Google Scholar]
- Berthold C. H. Ultrastructure of postnatally developing feline peripheral nodes of Ranvier. Acta Soc Med Ups. 1968;73(3-4):145–168. [PubMed] [Google Scholar]
- Fraher J. P. A quantitative study of anterior root fibres during early myelination. II. Longitudinal variation in sheath thickness and axon circumference. J Anat. 1973 Sep;115(Pt 3):421–444. [PMC free article] [PubMed] [Google Scholar]
- Fraher J. P., McDougall R. D. Macrophages related to leptomeninges and ventral nerve roots. An ultrastructural study. J Anat. 1975 Dec;120(Pt 3):537–549. [PMC free article] [PubMed] [Google Scholar]
- Fraher J. P. Quantitative studies on the maturation of central and peripheral parts of individual ventral motoneuron axons. I. Myelin sheath and axon calibre. J Anat. 1978 Aug;126(Pt 3):509–533. [PMC free article] [PubMed] [Google Scholar]
- Gutrecht J. A., Dyck P. J. Quantitative teased-fiber and histologic studies of human sural nerve during postnatal development. J Comp Neurol. 1970 Jan;138(1):117–129. doi: 10.1002/cne.901380109. [DOI] [PubMed] [Google Scholar]
- Hildebrand C. Ultrastructural and light-microscopic studies of the developing feline spinal cord white matter. II. Cell death and myelin sheath disintegration in the early postnatal period. Acta Physiol Scand Suppl. 1971;364:109–144. doi: 10.1111/j.1365-201x.1971.tb10980.x. [DOI] [PubMed] [Google Scholar]
- Knobler R. L., Stempak J. G., Laurencin M. Nonuniformity of the oligodendroglial ensheathment of axons during myelination in the developing rat central nervous system. A serial section electron microscopical study. J Ultrastruct Res. 1976 Jun;55(3):417–432. doi: 10.1016/s0022-5320(76)80097-4. [DOI] [PubMed] [Google Scholar]
- Knobler R. L., Stempak J. G., Laurencin M. Oligodendroglial ensheathment of axons during myelination in the developing rat central nervous system. A serial section electron microscopical sttudy. J Ultrastruct Res. 1974 Oct;49(1):34–49. doi: 10.1016/s0022-5320(74)90076-8. [DOI] [PubMed] [Google Scholar]
- Matthews M. A., Duncan D. A quantitative study of morphological changes accompanying the initiation and progress of myelin production in the dorsal funiculus of the rat spinal cord. J Comp Neurol. 1971 May;142(1):1–22. doi: 10.1002/cne.901420102. [DOI] [PubMed] [Google Scholar]
- Mori S., Leblond C. P. Electron microscopic identification of three classes of oligodendrocytes and a preliminary study of their proliferative activity in the corpus callosum of young rats. J Comp Neurol. 1970 May;139(1):1–28. doi: 10.1002/cne.901390102. [DOI] [PubMed] [Google Scholar]
- Peyronnard J. M., Terry L. C., Aguayo A. Schwann cell internuclear distances in developing rat unmyelinated nerve fibers. Arch Neurol. 1975 Jan;32(1):36–38. doi: 10.1001/archneur.1975.00490430058009. [DOI] [PubMed] [Google Scholar]
- Seggie J., Berry M. Ontogeny of interhemispheric evoked potentials in the rat: significance of myelination of the corpus callosum. Exp Neurol. 1972 May;35(2):215–232. doi: 10.1016/0014-4886(72)90148-3. [DOI] [PubMed] [Google Scholar]
- Stempak J. G., Knobler R. L. Bidirectionality in the tongue processes of the oligoendroglial cell investment of axons in the albino rat. Am J Anat. 1972 Oct;135(2):287–292. doi: 10.1002/aja.1001350213. [DOI] [PubMed] [Google Scholar]
- THOMAS P. K., YOUNG J. Z. Internode lengths in the nerves of fishes. J Anat. 1949 Oct;83(4):336-50, pl. [PMC free article] [PubMed] [Google Scholar]
- UZMAN B. G., NOGUEIRA-GRAF G. Electron microscope studies of the formation of nodes of Ranvier in mouse sciatic nerves. J Biophys Biochem Cytol. 1957 Jul 25;3(4):589–598. doi: 10.1083/jcb.3.4.589. [DOI] [PMC free article] [PubMed] [Google Scholar]
- VIZOSO A. D. The relationship between internodal length and growth in human nerves. J Anat. 1950 Oct;84(4):342–353. [PMC free article] [PubMed] [Google Scholar]
- Vizoso A. D., Young J. Z. Internode length and fibre diameter in developing and regenerating nerves. J Anat. 1948 Apr;82(Pt 1-2):110–134.1. [PMC free article] [PubMed] [Google Scholar]