Final answer:
The axon terminal of the neuron contains synaptic vesicles that release neurotransmitters into the synaptic cleft.
Step-by-step explanation:
The part of the neuron that contains synaptic vesicles which store and release neurotransmitters into the synapse is the axon terminal, also known as the terminal button of the presynaptic neuron. When an action potential reaches the axon terminal, it triggers the entry of calcium ions, which in turn causes the synaptic vesicles to fuse with the membrane and release their neurotransmitter contents into the synaptic cleft. There, neurotransmitters may bind to receptors on the dendrites of the postsynaptic neuron, facilitating neural communication.