Summary
Cross sections of A-α-motor stem fibres of the rat accessory nerve and of one of its branches, the N. musculi sternomastoidei were compared with cross sections of terminal branches of the same nerve, with respect to the axonal cross sectional areas and the number of neurotubules. The absolute number of neurotubules in a stem fibre was found to be on average five times that of one of its terminal branches, corresponding to the ratio of their axonal cross-sectional areas. Thus no significant differences could be found in the tubular density of large stem fibres and of small final branches. Taking into account that in the course of the terminal ramification the total axonal cross-sectional area increases (Zenker and Hohberg, 1973), the combined total of the numbers of neurotubules in all terminal branches of a single A-α-fibre of the nerve innervating the sternomastoid muscle surpasses the amount of tubules in the stem fibre on average about 11 times. These findings are incompatible with the idea of a constant number of neurotubules within a given axon and its branches. In accordance with recent biochemical studies of microtubular protein, our results indicate that neurotubules may be formed in axon branches far from the perikaryon.
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References
ANDRES, K. H. (1965)Tagung der Niederländischen und Deutschen Elektronenmikroskopischen Gesellschaften, Aachen.
AUCLAIR, W. and SIEGAL, B. (1966) Cilia regeneration in the sea urchin embryo; evidence for a pool of ciliary proteins.Science 154, 913–15.
ERLANGER, J. and GASSER, H. S. (1937)Electrical signs of nervous activity. Philadelphia: University of Pennsylvania Press.
FRIEDE, R. and SAMORAJSKI, T. (1970) Axon calibre related to neurofilaments and microtubules in sciatic nerve fibres of rats and mice.Anatomical Record 167, 379–88.
GRANIT, R. (1970)The basis of motor control. Academic Press: London, New York.
HINKLEY, R. E. and GREEN, L. S. (1971) Effects of halothane and colchicine on microtubules and electrical activity of rabbit vagus nerve.Journal of Neurobiology 2, 97–105.
KASHEF, R. (1966) The branching of myelinated nerves in vertebrates.Journal of Anatomy (Lond.)100, 927.
LEKSELL, L. (1945) The action potential and excitatory effects of the small ventral root fibres to skeletal muscle.Acta Physiologica Scandinavica 10, Supplement 31.
MARANTZ, R., VENTILLA, M. and SHELANSKI, M. (1965) Vindblastine-induced precipitation of microtubule protein.Science 165, 498–500.
MAYR, R. (1972) Organellenverteilung in peripheren Nervenfasern. 66.Verhandlungen der Anatomischen Gesellschaft 130, 391–402.
SCHNEPP, G., SCHNEPP, P. and SPAAN, G. (1971) Faseranalytische Untersuchungen an peripheren Nerven bei Tieren verschiedener Gröβe.Zeitschrift für Zellforschung und mikroskopische Anatomie 119, 77–98.
STANLEY, L. Twomey and SAMSON, F. E. Jun. (1972) Tubulin antigenecity in brain particulates.Brain Research 37, 101–8.
WEISS. P. A. and MAYR, R. (1971) Neuronal organelles in neuroplasmic (‘axonal’) flow.Acta neuropathologica (Berlin),Suppl. V, 198–206.
ZENKER, W. and HOHBERG, E. (1973) α-motorische Nervenfaser: Axonquerschnittsfläche von Stammfaser und Endästen.Zeitschrift für Anatomie und Entwicklungsgeschichte 139, 163–72.
ZENKER, W., MAYR, R. and GRUBER, H. (1973) Axoplasmic organelles: Quantitative differences between ventral and dorsal root fibres of the rat.Experientia 29, 77–78.
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Zenker, W., Hohberg, E. A-α-nerve-fibre: Number of neurotubules in the stem fibre and in the terminal branches. J Neurocytol 2, 143–148 (1973). https://doi.org/10.1007/BF01474716
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DOI: https://doi.org/10.1007/BF01474716