Answer: acetylcholine is released by axon terminals of the motor neurone.
Step-by-step explanation:
Neuromuscular junction is a type of chemical synapse that transmits signals from a motor neurone to a muscle fibre to ensure control of skeletal muscle contraction and voluntary movements.
The activities that occurs in this junction which eventually leads to muscle contraction includes'
- The arrival of action potential at the presynaptic terminal which leads to opening of calcium channels,
- Influx of calcium ions which causes neuromuscular vesicles to attach to presynaptic cell membrane,
- this leads to release of acetylcholine by the axon terminals which is the critical event that occurs in the neuromuscular Junction amongst other events. If acetylcholine is not released, end plate potential wont be achieved and no muscle contraction will occur. I hope this helps, thanks.