What is the swelling at the end of an axon branch, where the depolarisation wave stops and release begins, called? · Lobeworks/17

The presynaptic terminal, also called the bouton or axon terminal.

What is the swelling at the end of an axon branch, where the depolarisation wave stops and release begins, called?

The presynaptic terminal, also called the bouton or axon terminal. It is packed with vesicles of transmitter and its membrane carries the voltage-gated calcium channels clustered at the active zones, the release sites facing the receiving cell. The wave that arrives there is the same spike that travelled the axon; at the terminal it ends by opening those calcium channels.