Molecular architecture of the presynaptic terminal

Neurotransmitter release at the presynaptic terminal is one of the fundamental processes in neuronal communication. It is a complex process comprising signaling pathways that exert a precise spatio-temporal coordination to prepare and bring synaptic vesicles to exocytosis. While many molecular components involved have been identified, their direct observation at different stages of the neurotransmitter release is lacking. Three-dimensional imaging by electron tomography provided remarkable views of the synaptic vesicles and the cytomatrix. Imaging fully hydrated, vitrified samples allowed a direct visualization, precise localization and a quantitative characterization of pleomorphic synaptic vesicle-bound complexes in situ, as well as the elucidation of their function in the neurotransmitter release.