Study of the topographical distribution of different populations of motoneurons within rat's nucleus ambiguus, by means of four different fluorochromes.

The topographical neuronal distribution within the rat nucleus ambiguus has been studied with the simultaneous retrograde labeling technique by means of four different fluorochromes injected within the various muscles and/or nerves of the oro-pharyngeal region. This technique has permitted the identification of several types of neurons along the same coronal plane. Most were motoneurons innervating the various muscles of the upper airway, including pharyngeal constrictor, stylopharyngeal, intrinsic laryngeal and the upper portion of the esophagus. Some neurons may have been preganglionic parasympathetic neurons. No evidence of axonal branching of any of the labeled motoneurons or parasympathetic neurons was found.