The vesicles are represented by blue and white circles at the top left. The white circles are empty and the blue ones contain a neurotransmitter. "Full" vesicles move toward the membrane of the nerve terminal, represented by the overall outline of the figure, where they attach and fuse into the terminal membrane, thereby releasing the transmitter into the space between neurons, the synaptic cleft. This release is illustrated by a blue omega-shaped structure at the bottom of the terminal membrane. When a vesicle becomes "empty," the vesicle membrane is retrieved into the terminal -- white circles on the right -- and then recycled back to the release sites, which are illustrated as red bars.