Electron Microscopy: Two Major Synaptic Types on Spinal Motoneurons

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Science  04 Mar 1966:
Vol. 151, Issue 3714, pp. 1093-1094
DOI: 10.1126/science.151.3714.1093


Two major types of synaptic bulbs are defined on the motoneuron surface of the monkey, on the basis of content of agranular "synaptic" vesicles of two distinct kinds. Both types are present on dendritic as well as perikaryal surface. Because of the approximately equal numbers, the hypothesis that one type is excitatory and the other inhibitory naturally arises.