<Tr> <Th> TH </Th> <Td> H2. 00.06. 2.00004 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terms of microanatomy (edit on Wikidata) </Td> </Tr> <P> 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 "terminal bouton". Up to 130 vesicles can be released per bouton over a ten - minute period of stimulation at 0.2 Hz . In the visual cortex of the human brain, synaptic vesicles have an average diameter of 39.5 nanometers (nm) with a standard deviation of 5.1 nm . </P> <P> Synaptic vesicles are relatively simple because only a limited number of proteins fit into a sphere of 40 nm diameter . Purified vesicles have a protein: phospholipid ratio of 1: 3 with a lipid composition of 40% phosphatidylcholine, 32% phosphatidylethanolamine, 12% phosphatidylserine, 5% phosphatidylinositol, and 10% cholesterol . </P>

In the presynaptic neuron neurotransmitter release from vesicles is dependent on