Synapses of the central nervous system

The cytological problems presented by the synapse were carefully con-sidered by Bodian (6) in his review of 1942. He indicated that it is desirable to know more about "the ultrastructure of the membranes concerned, the quantitative relations existing between surfaces of axon terminals and the surfaces Of cells of termination, the intimate relationships of myelin and of glia to synaptic surfaces, thetypes, approximate numbers, and specific sites of origin of endings on cells of each type, the lectrical properties of cellular elements and intracellular materials, and the localized concentrations and site of action of both drugs and physiological substances which may produce or modify neuronal excitation, under varying conditions. " Thanks to recent advances in neurophysiology (11), neuropharmacology (12, 22), and neuro-anatomy, it is now possible to give answers to some of these problems, al-though the answers are by no means complete. The following paper reports an electron microscopic study of synaptic terminals in the medulla oblongata, cerebellar cortex, and cerebral cortex of the rat. The information presented i