Monoaminergic neurons in the nervous system of crustaceans.

Certain neurons in the nervous system of the malacostracan crustaceans give rise to a predominantly green and a sparse yellow fluorophore in the histochemical fluorescence method of Falck-Hillarp. The same applies to the whole of Crustacea. The green fluorophore is probably a catecholamine; the yellow to brown-yellow has not yet been identified. The biogenic amine responsible for the green fluorescence, besides being found in diffusely distributed fibres, also appears in distinct areas of fibre concentrations in the central nervous system. The protocerebrum of the malacostracans contains three areas: the central body and two areas in the top of the brain, one anterior and one posterior. The latter two are not recognized as separate areas in ordinary histological preparations. In addition, the optic neuropiles are fluorescent, some with a distinct stratification of the fluorophore. The deuto- and tritocerebrum and the ventral nerve cord also contain monoaminergic neurons. Of the brightly fluorescent areas in the whole of Crustacea, only the central body consistently exists in all species. The other areas of concentrated fluorescent neuropile are restricted to smaller taxonomic units and differ from each other.