Neuromuscular junction. Light micrograph of a motor end plate, the neuromuscular junction, or connection point between a motor neurone axon and the skeletal muscle fibres that it controls (horizontal tissue band). The end plate consists of a cluster of small swellings or boutons. When activated, the boutons release neurotransmitter chemicals. These diffuse across the gap (the synapse) between nerve and muscle fibre and interact with receptors in the muscle cell, activating it. The end of a motor neurone axon divides into branches, each one terminating on a different muscle fibre. A single axon thereby has the ability to control up to several hundred muscle fibres.