Cellular localization of monoamines in the upper brain stem of the pigeon

Abstract

With the help of a highly sensitive and specific fluorescence method developed by Falck and Hillarp, in combination with a pharmacological approach, it has been possible to demonstrate the presence in birds of specific Neurons of two distinctly different types, which in all probability form and store a primary catcholamine and 5‐hydroxytryptamine respectively. The amines are in low concentrations in the cell bodies and axons but stored in very high concentrations in the terminals, especially in the abundant varicosities. At least three large ascending monoamine systems appear to be present within the upper brain stem. Many — if not most — of the ascending fibers arise in all probability from cell bodies within the mesencephalon and run rostrally mainly in the medial forebrain bundle. Two of the Neuron systems produce and store a primary catecholamine, one probably giving rise mainly to terminals within the hypothalamus and the preoptic area, the other within the corpus striatum. The remaining system produces and stores 5‐hydroxytryptamine. The modified ependyma seems to consist — at least partly — of two types of cells forming and storing either a primary catecholamine or 5‐hydroxytryptamine.