EVIDENCE FOR 5-HYDROXYTRYPTAMINE IN NEURONS IN THE GUT OF THE TOAD, BUFO-MARINUS

Abstract

The stomach, small intestine and large intestine of the toad, Bufo marinus, were processed for formaldehyde-induced fluorescence histochemistry. After extrinsic denervation or pretreatment with 6-hydroxydopamine to remove catecholamine fluorescence, yellow fluorescence typical of 5-hydroxytryptamine was observed in neurones in the small intestine only. The cell bodies and their processes were confined to the myenteric plexus. Additional pretreatment with 5-hydroxytryptamine enhanced the fluorescence of neurones in the small intestine and revealed yellow-fluorescent nerve fibres, but not cell bodies, in the longitudinal and circular muscle layers and myenteric plexus of the large intestine. N..