The Characterization of Monoaminergic Nerve Terminals in the Brain by Fine Structural Cytochemistry

It is now accepted that noradrenaline (NA) acts as the transmitter of the postganglionic adrenergic neuron (Euler, 1971) while in the brain the monoamines NA, dopamine (DA) and 5-hydroxytryptamine (5-HT) are putative transmitters (Vogt, 1971). Fluorescence microscopy has shown that the amines are distributed throughout the neuron (Eranko and Harkonen, 1963; Falck, 1962) although they are to be found in their greatest concentration in highly fluorescent varicosities or terminals which are noticeable in the course of the terminal axon and it is there that the transmitter appears to be released in close proximity to the effector cell e.g. smooth muscle or adjacent neuron.