title: Serotonin-containing axon terminals in the hypoglossal nucleus of the rat. An immuno-electronmicroscopic study.
abstract: The morphology and distribution of serotonin-containing axon terminals in the rat hypoglossal nucleus (XII) was investigated immunocytochemically at the electron microscopic level. Serotonin-positive profiles were found throughout all regions of XII and included unmyelinated axons, varicosities and axon terminals. Most labeled profiles (68.1%) were nonsynaptic unmyelinated axons and varicosities, while synaptic profiles, ending on dendrites and somata, were seen less frequently (28.7%). The majority of labeled axon terminals (76.9%) ended on small-to-medium-sized dendrites. Most axodendritic terminals contained small, round agranular vesicles (20-55 microns), several large (60-100 microns) dense core vesicles, and were associated with a pronounced asymmetric postsynaptic specialization. By contrast, labeled axosomatic terminals were seen less often than those ending on dendrites (23.0%). Axosomatic terminals typically contained small, round, agranular and large dense core vesicles and were associated with a symmetric or no postsynaptic specialization. These results provide the structural substrates for elucidating the functional role of serotonin in tongue control.
authors.affiliation: Department of Structural and Cellular Biology, University of South Alabama, College of Medicine, Mobile 36688.
authors.forename: L D
authors.initials: LD
authors.lastname: Aldes
authors.forename: L A
authors.initials: LA
authors.lastname: Marco
authors.forename: R B
authors.initials: RB
authors.lastname: Chronister
mesh_terms: D000818:Animals; D001369:Axons / Q000032:analysis* / Q000648:ultrastructure; D005260:Female; D007002:Hypoglossal Nerve / Q000032:analysis* / Q000648:ultrastructure; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000032:analysis* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000032:analysis*
chemical_list: D012701:Serotonin