Topography of cholinergic perikarya and nerve fibres as well as cholinergic vesicles in the rat duodenum

Abstract

Using the acetylthiocholine staining method, it was possible to visualize acetylcholinesterase (AChE)-stained neuronal cell bodies and nerve endings as well as AChE-positive vesicles in the rat duodenum. AChE-reactive perikarya were seen with certainty only in the myenteric plexus. They were 40 μm in diameter and were mostly localized in groups within the ganglia (3–6 neurons per ganglion). Some thick, AChE-reactive nerve processes, running over a long distance in interconnecting nerve fibre strands, had their origin from AChE-containing myenteric plexus perikarya. AChE-stained nerve fibres were detected in the myenteric and submucosal plexus as well as in the longitudinal and circular smooth muscle cell layer. AChE-positive nerve fibres were in close contacts with blood vessels, probably arterioles, Brunner's gland cells and epithelial cells. A conspicuously high density of AChE-positive nerve fibres was noted in the longitudinal smooth muscle layer, while AChE-stained nerve fibres were visualized only sporadically in the circular smooth muscle layer. Some Brunner's gland cells and epithelial cells contained AChE-reactive vesicles, which were constantly localized on the basal cell portion. The present findings might indicate that acetylcholine possesses important physiological roles as neurotransmitter and/or neuromodulator in the rat duodenum.