In a
neuron,
synaptic vesicles (or
neurotransmitter vesicles) store various
neurotransmitters that are
released at the
synapse. The release is regulated by a
voltage-dependent calcium channel.
Vesicles are essential for propagating
nerve impulses between neurons and are constantly recreated by the
cell. The area in the
axon that holds groups of vesicles is an
axon terminal or "bouton". Up to 130 vesicles can be released per bouton over a ten-minute period of stimulation at 0.2 Hz. In the human brain region
V1 synaptic vesicles have an average diameter of 39.5 nanometers with a standard deviation of 5.1 nanometers.