title: Catecholamine-containing axon terminals in the hypoglossal nucleus of the rat: an immuno-electronmicroscopic study.
abstract: A correlative light and electron microscopic investigation was undertaken to determine the morphology and distribution of catecholamine (CA)-containing axon terminals in the hypoglossal nucleus (XII) of the rat. This was accomplished immunocytochemically with antibody to tyrosine hydroxylase (TH). The major findings in this study were the following: 1) Immunoreactive profiles were found throughout XII and included unmyelinated axons, varicosities, axon terminals and dendrites; 2) Nonsynaptic immunoreactive profiles (preterminal axons, varicosities) were more frequently observed (55.2%) than synaptic profiles (43.5%); 3) CA-containing axon terminals ending on dendrites were more numerous (71.8%) than those synapsing on somata (25.4%) or non-labeled axon terminals (2.7%); 4) The morphology of labeled axon terminals was variable. Axodendritic terminals typically contained numerous small, round agranular vesicles, a few large dense-core vesicles and were associated with either a symmetric or no synaptic specialization, axosomatic terminals were often associated with a presynaptic membrane thickening or a symmetric synaptic specialization and contained small, round and a few elliptical-shaped vesicles, while axoaxonic synapses formed asymmetric postsynaptic specializations; and 5) CA-positive dendritic processes were identified in XII. These findings confirm the CA innervation of XII, and suggest a complex, multifunctional role for CA in controlling oro-lingual motor behavior.
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: B
authors.initials: B
authors.lastname: Shaw
authors.forename: R B
authors.initials: RB
authors.lastname: Chronister
authors.forename: J W
authors.initials: JW
authors.lastname: Haycock
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism*; D002395:Catecholamines / Q000502:physiology*; D005260:Female; D007002:Hypoglossal Nerve / Q000166:cytology* / Q000378:metabolism; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000648:ultrastructure; D009411:Nerve Endings / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D014446:Tyrosine 3-Monooxygenase / Q000276:immunology
chemical_list: D002395:Catecholamines; D014446:Tyrosine 3-Monooxygenase