Confocal image of axons (green) making contact with muscle fibers at neuromuscular junctions. As seen here more than one nerve fiber initially contacts each muscle fiber. As development proceeds, the mature innervation pattern is established where only one motor axon contacts each muscle fiber. This transition is called synapse elimination and is thought to involve of competition between the neurons. The neurotransmitter acetylcholine (red) sends the signals from the nerve to makes the muscle contract.