EXCITATORY AND INHIBITORY SYNAPSES IN THE CAT SPINAL CORD

Abstract

New Wlion methods in electron microscopy using formalin have revealed that there are 2 different types of synapses in the anterior horn of the cat spinal cord. The one type of synapse contains vesicles of spherical shape of about 500 A diameter, while the other synapse contains ellipsoidal vesicles of the smaller size than the former. In comparison with Purkinje cells in the cat''s cerebellum which have been identified as having excitatory (spherical) and inhibitory (ellipsoidal) synapses on the dendrlte and soma of neuron respectively, the motoneuron of the cat''s anterior horn has 2 types of synapses; one contains excitatory synaptic vesicles (spherical) and the other contains inhibitory synaptic vesicles (ellipsoidal).