This application proposes structural and functional analyses of the internal organization of the mammalian muscle spindle. Neural and muscular features of spindles will be compared: among cat, monkey and man; among functionally different muscles of monkey; and among single isolated human spindles from which afferent responses have been elicited by stimulation of known fusimotor axons. The proposed research addresses: a) whether efferent and afferent features of the human spindle are similar to those of spindles in cat or monkey; b) whether particular, anatomy-dependent motor tasks (flexion vs. extension) necessitate a particular internal organization of spindle; c) whether 'mixed' afferent fusimotor actions have a neural or muscular origin; d) the nature of factors that determine the neural organization of human spindle; e) how the anatomical features of innervation of individual intrafusal fibers and variability in structure along the length of fibers, translate into functional attributes of afferents in single, isolated human spindles. Motor and sensory innervation of spindles are reconstructed by light microscopy of serial transverse sections of plastic-embedded material. Ultrastructure of intrafusal fibers is analyzed qualitatively and quantitatively from electron micrographs. Structural properties of spindles are correlated directly with afferent responses in single, isolated organs in vitro. The study represents the first comparative analysis of the nerve supply of spindles in different muscles and in different species of mammal, and the first comprehensive anatomical/physiological study of the human muscle spindle. The work is essential for clarifying the role of efferent and afferent nerve supplies of the mammalian spindle in controlling movement and posture.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Neurology B Subcommittee 1 (NEUB)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Boston University
Schools of Medicine
United States
Zip Code
Stephens, H; Walro, J M; Kucera, J (1992) Morphometric analysis of coated vesicles in developing rat muscle spindles. Physiol Res 41:173-90
Kucera, J; Walro, J M; Reichler, J (1991) Neural organization of spindles in three hindlimb muscles of the rat. Am J Anat 190:74-88
Kucera, J; Walro, J M (1989) Postnatal expression of myosin heavy chains in muscle spindles of the rat. Anat Embryol (Berl) 179:369-76
Kucera, J; Walro, J M; Reichler, J (1989) Role of nerve and muscle factors in the development of rat muscle spindles. Am J Anat 186:144-60
Kucera, J; Walro, J M (1989) Nonuniform expression of myosin heavy chain isoforms along the length of cat intrafusal muscle fibers. Histochemistry 92:291-9
Kucera, J; Walro, J M (1988) The effect of neonatal deafferentation or defferentation on myosin heavy chain expression in intrafusal muscle fibers of the rat. Histochemistry 90:151-60
Peng, H B; Chen, Q (1988) Localization of calcitonin gene-related peptide (CGRP) at a neuronal nicotinic synapse. Neurosci Lett 95:75-80
Kucera, J; Walro, J M; Reichler, J (1988) Motor and sensory innervation of muscle spindles in the neonatal rat. Anat Embryol (Berl) 177:427-36
Kucera, J; Walro, J M; Reichler, J (1988) Innervation of developing intrafusal muscle fibers in the rat. Am J Anat 183:344-58
Kucera, J; Walro, J M (1988) The effect of neonatal deafferentation or deefferentation on the immunocytochemistry of muscle spindles in the rat. Neurosci Lett 95:88-92

Showing the most recent 10 out of 19 publications