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The effects of chronic denervation on spindle discharge patterns and morphology in isolated costocutaneous muscles of garter snakes
Author(s) -
Fukami Y.,
Ridge R. M. A. P.
Publication year - 1971
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.901430202
Subject(s) - denervation , tonic (physiology) , biology , anatomy , neurofilament , ultrastructure , sensory system , neuroscience , immunohistochemistry , immunology
Abstract Experiments on spindles in normal and chronically denervated lateral costocutaneous muscles of snakes are described. The discharge patterns in response to stretch of tonic and phasic spindles are compared between normal spindles and those denervated for various periods of time. The main findings are that spindle function is lost after denervation periods of about 150 hours (the animal being kept at 30°C during the denervation period), and that prior to this (130–140 hours) both tonic and phasic spindles lose their ability to discharges; i.e., they become totally adapting. Electronmicrographs, prepared mainly from material used in the physiological experiments, reveal certain structural changes occurring in parallel with the physiological changes. These consist of increase of neurofilaments, swelling and increasing electron density of mitochondria and appearance of electron‐dense bodies in the sensory ending; these changes occur at times when the spindles are still functioning, though in a modified way. Later the gap between nerve ending and underlying intrafusal fiber is invaded by satellite cell processes. Eventually the nerve endings totally disappear.