part of part of axon terminus axon terminal specialization Terminal inflated portion of the axon, containing the specialized apparatus necessary to release neurotransmitters. The axon terminus is considered to be the whole region of thickening and the terminal button is a specialized region of it. axon terminal NIF_Subcellular:nlx_subcell_20090512 nerve ending cellular_component GO:0043679 neuron projection terminus presynapse distal axon