Localization of monoamines in the corpora cardiaca and the hypocerebral ganglion of locusts.

The Falck-Hillarp method reveals yellow and green fluorescent areas in the neurohemal part of the corpora cardiaca. Some neurons and the neuropile of the hypocerebral ganglion appear green. The localization of triatiated serotonin taken up and stored in the corpora cardiaca was studied radioautographically in vivo and in vitro with the use of low concentrations of tritiated serotonin. In the neural part of the corpora cardiaca, fibers with 100 nm dense granules were shown to be indolaminergic. Fibers containing 200 nm dense granules and 250 nm clear vesicles are thought to be catecholaminergic.