Fluorescence Histochemical Demonstration of Adrenergic Nerve Fibers in the Vagus Nerve of Cats and Dogs

The cervial vagus nerves of the mammalians are known to be composed of the fol lowing five, functionally different fibers: 1) general somatic afferent fibers, 2) general visceral afferent fibers, 3) specific visceral afferent fibers, 4) general visceral efferent fibers and 5) specific visceral efferent fibers (1).The general visceral efferent fibers originating from the dorsal motor nucleus of the vagus in the medulla oblongata are regarded to be cholinergic in nature.But fluorescence histochemical studies showed that green-fluores cent noradrenaline terminals became visible in the part of this nucleus after giving 1-dopa to rats (2).Cholinergic impulses conducted in the vagus nerve give rise to the inhibition of cardiac rate and contractility, the relaxation of gastrointestinal sphincters and also to the increase of gastrointestinal motility and tone.