NEUROMUSCULAR SYNAPSES IN COCKROACH EXTENSOR TIBIAE MUSCLE

The fine structure of fast-axon and slow-axon neuromuscular synapses was investigated in the extensor tibiae muscle of the cockroach (Periplaneta americana), using muscle fibres which were found to be innervated by only one of the two motor axons. Synapse-bearing terminals of the fast axon are larger and form more synaptic contacts than those of the slow axon. There is no difference in the synaptic vesicles of the two axons. Synaptic vesicles are often seen in association with axon filaments or tubules. Extra-axonal vesicles are sometimes found in close association with the axons. © 1969.