Synaptic contacts at nodes of ranvier in central nervous tissue

Parietal cortex, hippocampus and reticular formation of the medulla of normal rabbits were primarily fixed by glutaraldehyde perfusion followed by phosphate buffered osmium tetroxide. In electron micrographs of this material the central nodes of Ranvier exhibitedmost of the features of peripheral nodes. Branching was observed at central nodes which resembled branching of the myelinated axons at peripheral nodes. Two types of synapses were observed at the node. In the first type the axon formed a process which ended in a bouton, synapsing with a dendritic spine, while in the other type the axon bulged at the node to form the bouton.