<P> Axon terminals (also called synaptic boutons) are distal terminations of the branches of an axon . An axon nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses (called "action potentials") away from the neuron's cell body, or soma, in order to transmit those impulses to other neurons . </P> <P> Neurons are interconnected in complex arrangements, and use electrochemical signals and neurotransmitter chemicals to transmit impulses from one neuron to the next; axon terminals are separated from neighboring neurons by a small gap called a synapse, across which impulses are sent . The axon terminal, and the neuron from which it comes, is sometimes referred to as the "presynaptic" neuron . </P> <P> Neurotransmitters are packaged into synaptic vesicles that cluster beneath the axon terminal membrane on the presynaptic side of a synapse . The axonal terminals are specialized to release the neurotransmitters of the presynaptic cell . The terminals release transmitter substances into a gap called the synaptic cleft between the terminals and the dendrites of the next neuron . The information is received by the dendrite receptors of the postsynaptic cell that are connected to it . Neurons don't touch each other, but communicate across the synapse . </P>

By what means of membrane transport does the neurotransmitter leave the axon terminal