title: Serotonergic innervation on the motoneurons in the mammalian brainstem. Light and electron microscopic immunohistochemistry.
abstract: A comparative study of serotonergic innervation on motoneurons in the brainstem of various mammals (mouse, rat, guinea pig, dog, cat and monkey) was carried out using a sensitive immunohistochemical method. Except for the extraocular muscle nuclei, the motor nuclei of the cranial nerves received rich inputs from serotonin neurons, in all species examined--rodent, carnivore and primate. The motoneurons of the monkey were innervated by varicose serotonin fibers, in a manner different from that of other species, i.e. their cell bodies and proximal dendrites were tightly encircled by a large number of serotonin-containing varicose fibers. At the ultrastructural level, a predominant population of axosomatic contacts was confirmed in the cranial motor nuclei of the monkey, particularly in the nucleus ambiguus.
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology* / Q000648:ultrastructure; D002415:Cats; D003391:Cranial Nerves; D003712:Dendrites; D004285:Dogs; D006168:Guinea Pigs; D006651:Histocytochemistry; D008251:Macaca; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000166:cytology* / Q000648:ultrastructure; D009801:Oculomotor Muscles / Q000294:innervation; D051381:Rats; D012701:Serotonin / Q000032:analysis*
chemical_list: D012701:Serotonin