The morphological effects of daily bouts of exercise and denervation on teres minor intrafusal muscle fibers were investigated in male Sprague-Dawley rats. After denervation, nuclear bag and nuclear chain muscle fiber cross-sectional area atrophied only 25 and 33% of the amount experienced by extrafusal fibers. Of the two fiber types, the nuclear chain fibers appeared to be more responsive to the effects of exercise than the nuclear bag fibers; however, this trend for enlargement had no statistical significance. Length measurements did not reveal any marked changes of any fiber type to the experimental conditions of this study. It was concluded that the possible differences in function and innervation of the nuclear bag and nuclear chain fibers could partly account for these findings.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Adams, R. D., Denny-Brown, D., Pearson, C. M.: Diseases of Muscles: A Study in Pathology. New York: Hoeber 1953.
Barker, D.: The Structure and Distribution of Muscle Receptors. Symposium on Muscle Receptors, pp. 227–240. Hongkong: University Press 1962.
—, The Motor Innervation of the Mammalian Muscle Spindle. Muscular Afferents and Motor Control, pp. 51–58. Ed. by Ragnar Granit. New York: Wiley and Sons 1966.
Boyd, I. A.: The motor innervation of mammalian muscle spindles. J. Physiol. (Lond.)159, 7–9P (1961).
—: The structure and innervation of the nuclear bag muscle fibre system and the nuclear chain muscle fibre system in mammalian muscle spindles. Philosophical Transactions of the Royal Society, Series B,245, 81–136 (1962).
Bridgman, C. F., Shumpert, E. E., Eldred, E.: Insertions of intrafusal fibers in muscle spindles of the cat and other mammals. Anat. Rec.164, 391–401 (1969).
Cazzato, G., Walton, J. N.: The pathology of the muscle spindle: A study of biopsy material in various muscular and neuromuscular diseases. J. neurol. Sci.7, 15–70 (1968).
Cooper, S.: The Behavior of Spindle Receptors During Muscle Stretch. Symposium on Muscle Receptors, pp. 121–124. Ed. by David Barker. Hongkong: Hongkong Press 1962.
Eyzaguirre, C.: Properties of Intrafusal Muscle Fibers of Amphibians and Mammals. Control and Innervation of Skeletal Muscle, pp. 69–82. Ed. by B. L. Andres. London: Livingstone 1966.
Ferguson, G. A.: Statistical Analysis in Psychology and Education. New York: McGraw-Hill Book 1966.
Gutman, E., Zelena, J.: Morphological Changes in the Denervated Muscle. The Denervated Muscle, pp. 57–102. Prague: Publishing House of the Czechoslovak Academy of Sciences 1962.
Matthews, P. B. C.: Muscle spindles and their motor control. Physiol. Rev.44, 219–288 (1964).
Merton, P. A.: The silent period in a muscle of the human hand. J. Physiol. (Lond.)114, 183–198 (1951).
Patel, A. N., Lalitha, V. S., Dastur, D. K.: The spindle in normal and pathological muscle. Brain91, 737–750 (1968).
Smith, R. S.: Properties of Intrafusal Muscle Fibers. Muscular Afferents and Motor Control, pp. 69–80. Ed. by Ragnar Granit. New York: Wiley and Sons 1966.
Tipton, C. M.: Training and bradycardia in rats. Amer. J. Physiol.209, 1089–1094 (1965).
Tower, S. S.: Atrophy and degeneration in the muscle spindle. Brain55, 77–90 (1932).
Supported in part by funds provided by the Graduate College.
About this article
Cite this article
Maynard, J.A., Tipton, C.M. The effects of exercise training and denervation on the morphology of intrafusal muscle fibers. Int. Z. Angew. Physiol. Einschl. Arbeitsphysiol. 30, 1–9 (1971). https://doi.org/10.1007/BF00693719
- Muscle Spindle
- Exercise Training