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Updated: May 31, 2026

Characterization of Neuromuscular Junctions in Mice by Combined Confocal and Super-Resolution Microscopy
Published on: December 8, 2021
Amplification of neuromuscular transmission by postjunctional folds
1Department of Physiology C240, University of Colorado School of Medicine, Denver, Colorado 80262, U.S.A.
Abstract:
Previously, suggestions have been made that postjunctional folds at the vertebrate motor end plate might, in some way, serve to enhance neuromuscular transmission. This suggestion was examined quantitatively using a model junction with geometry similar to that seen in mammalian 'fast twitch' muscles. It was found that the depolarization produced at the top of an interfold by a quantum of acetylcholine is significantly greater than that produced in the absence of folds because of the series resistance of the interfold myoplasm. As a result, voltage-sensitive sodium channels in the postsynaptic membrane are activated more readily. In the model, activation of as few as four interfolds by eight quanta is sufficient for excitation to spread to the remainder of the muscle. With no folds, 19 quanta are required.
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