Synaptic development: insights from Drosophila.

In Drosophila, the larval neuromuscular junction is particularly tractable for studying how synapses develop and function. In contrast to vertebrate central synapses, each presynaptic motor neuron and postsynaptic muscle cell is unique and identifiable, and the wiring circuit is invariant. Thus, the full power of Drosophila genetics can be brought to bear on a single, reproducibly identifiable, synaptic terminal. Each individual neuromuscular junction encompasses hundreds of synaptic neurotransmitter release sites housed in a chain of synaptic boutons. Recent advances have increased our understanding of the mechanisms that shape the development of both individual synapses--that is, the transmitter release sites including active zones and their apposed glutamate receptor clusters--and the whole synaptic terminal that connects a pre- and post-synaptic cell.