part_of part of part of cellular_component axon presynaptic cell presynaptic terminal Planarian_Anatomy 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 bouton is a specialized region of it. PMID:23903188 GO:0043195 pre-synaptic terminal https://orcid.org/0000-0003-2569-1939 | https://orcid.org/0000-0002-7535-4407