Synaptic cleft

At a chemical synapse, one neuron releases neurotransmittermolecules into a small space (the synaptic cleft) that is adjacent to the postsynaptic cell (e.g., another neuron). The neurotransmitter molecules are contained within small sacs called synaptic vesicles, and are released into the synaptic cleft by exocytosis. These molecules then bind to neurotransmitter receptors on the postsynaptic cell. Finally, to terminate its action, the neurotransmitter is cleared from the cleft through one of several mechanisms, including enzymatic degradation or re-uptake, by specific transporters, either into the presynaptic cell or to neuroglia.