A non-adrenergic nerve ending containing small granular vesicles in the guinea-pig gut.

Two distinct types of small granular vesicle(SGV)-containing nerve ending are described in the gastrointestinal tract of the guinea-pig. One of these types of ending accumulates 5- and 6-hydroxydopamine (OHDA) and is therefore adrenergic. The other type remains unchanged after in vivo exposure to these drugs. The widespread distribution of this nerve in the smooth muscle layers of the large and small bowel suggests that it may play a role in gut motility.