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Morphology and morphometry of motor endings on macaque intrafusal fibers
Author(s) -
Sahgal Vinod,
Subramani Venka,
Sahgal Sudarshan
Publication year - 1990
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1052050309
Subject(s) - biology , morphology (biology) , anatomy , macaque , free nerve ending , neuroscience , zoology
The ultrastructural studies have shown three types of motor endings in the macaque intrafusal fibers: (1) unindented axon terminals with smooth or shallowly folded postsynaptic membrane; (2) indented terminals with few postsynaptic folds; and (3) indented terminals with heavily folded postsynaptic membrane. The terminals on bag 1 and chain fibers were generally more indented than those on the bag 2 fibers. Deeply indented terminals with highly folded postsynaptic membranes were noticed on the bag 1 and chain endings in spindles from lumbrical but not the biceps muscle. In the individual intrafusal fibers from the biceps and lumbrical spindles, the degree of indentation did not correlate with the extent of postsynaptic folding (P>.01). Endings on bag 1 and chain fibers in the lumbrical spindles showed a positive correlation between indentation of terminals and their distance from the primary sensory endings (P<.01), whereas the lumbrical bag 2 endings and the biceps intrafusal endings did not (P>.01). The shape of the intrafusal motor endings thus is independent of their location but dependent on the type of intrafusal fibers.