POSTSYNAPTIC MEMBRANE FOLDS OF THE FROG NEUROMUSCULAR-JUNCTION VISUALIZED BY SCANNING ELECTRON-MICROSCOPY

We have used a scanning electron microscope to study the morphology of the postsynaptic folds in frog muscle. These folds were exposed by digesting muscles in collagenase or osmium tetroxide. During digestion the connective tissue and basement lamina were removed and the presynaptic nerve terminal pulled away from the muscle surface to reveal one or more concave junctional grooves, within which the folds in the postsynaptic membrane could be clearly seen. In places the folding patterns were more complex than could be inferred from single thin-section electron micrographs. The ease with which the postsynaptic folds of vertebrate muscles can be directly observed using this technique now makes it possible to investigate subtle changes in their structure during synaptogenesis, denervation or disease. © 1979.