Neuromuscular junction. Transmission electron micrograph (TEM) of a neuromuscular junction. A neuromuscular junction, or motor end plate, is the connection point between a motor neurone axon and the skeletal muscle fibres (right of image) that it controls. Neuromuscular junctions show unique architectures. Ramifications of the axon terminate in knob-like end pieces, each of which is embedded in a shallow depression on the surface of the muscle fibre. When activated, the neurone releases neurotransmitter chemicals. These diffuse across the gap (the synapse) between the nerve and muscle fibre and interact with receptors in the muscle cell, activating it. The end of a motor neurone axon (purple) 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. Magnification: x5, 000 at 10cm wide