Adrenergic innervation of the alimentary canal.

Abstract

The adrenergic innervation of the subdiaphragmatic digestive tract of the rabbit, the rat and the guinea-pig, has been studied by means of the histochemical technique of Falck and Hillarp. Auerbach's and Meissner's plexuses are richly supplied by adrenergic fibres both in the ganglia and in the connecting tracts. The distribution of adrenergic fibres appears fairly uniform within the myenteric ganglia of the different subdivisions. No adrenergic intramural neurons are found except in Auerbach's plexus of the proximal colon of the guinea-pig where particularly tightly packed clusters of pericellular baskets are also found. Adrenergic fibres are present within the circular muscle layer of all regions, and in the taeniae of the caecum of the guinea-pig. In the cardiac and the anal sphincters there is an exceedingly dense innervation of longitudinal and circular muscle. The glands of the mucous coat in the different parts of the gut are richly supplied by adrenergic nerves. There is a dense innervation of intestinal arteries. It is suggested that postganglionic adrenergic axons have a direct action on the muscle and that they indirectly affect the muscle by an action on intramural ganglia.