HISTOFLUORESCENT LOCALIZATION OF SEROTONIN AND DOPAMINE IN THE NERVOUS SYSTEM AND GILL OF<i>MYTILUS EDULIS</i>(BIVALVIA)

Abstract

Monoamine localization was accomplished in Mytilus edulis by the use of histofluorescence. Intracellular stores of dopamine and serotonin were found to be synthesized in the proper neuron and transported down the axon to the terminal varicosities.Most of the cells in the cortex of the cerebral and visceral ganglia were non-fluorescent. Of the fluorescent cells, serotonin predominated in the cerebral ganglion and dopamine predominated in the visceral ganglion. There was a net flow of serotonin in the cerebro-visceral connective from the cerebral to the visceral ganglion and a net flow of dopamine in the opposite direction.Serotonin fluorescence was localized in intracellular granules in neurons and blood cells. Dopamine fluorescence was distributed homogenously in neurons and in the supporting rod of the gill. The visceral ganglion supplies the gill with nerve fibers of both types.Exogenously supplied serotonin and dopamine were taken up by both kinds of nerve cells and by some other tissues. Endogenous stores of both amines were altered in content and distribution by reserpine and by nialamide.The distribution of monoamine in the nervous system and gill lends further support to the notion of a dual innervation mechanism controlling ciliary activity in the gill.