[Morphologic changes in synapses following conduction block in a medium of diminished ionic strength]

The moment of the conduction block was determined in the 10th sympathetic ganglion of the frog with the help of electrophysiological control of the total synaptic activity. After supravital staining with methylene blue the morphology of the synaptic pericellular apparatus was studied. It has been shown that most of synapses are in the intermediate phase (after Majorov) and have swollen, loosing their dye synaptic bouttons against the background of non-stained bodies of nerve cells. A supposition is made that due to the presence of single synapses with less pronounced changes under complete block of conducting it can not be excluded that the block may develop in the transition of the synapse from the phase of stained pericellular apparatus into an intermediate phase.