The catecholamine-containing neurons in the cat dorsolateral pontine tegmentum: Distribution of the cell bodies and some axonal projections

The distribution and the projections of the catecholamine-containing neurons in the dorsolateral pontine tegmentum of the cat was studied by the fluorescent histochemical technique of Falck and Hillarp. In contrast to the rat locus coeruleus nucleus which is well-defined and consists of densely packed norepinephrine-containing cells, the distribution of the catecholamine cells in the cat pons is more diffuse and more extensive. This extensiveness of the NE system in the pons is mainly due to the existence of catecholamine cells in the 'subcoeruleus' nucleus and in the area which surrounds the brachium conjunctivum. The catecholamine cells in the LC nucleus constitute the main source for the dorsal ascending NE pathway; the same cells also innervate the dorsal raphe nucleus and cerebellar cortex via axon collaterals. The catecholamine neurons in the medial locus coeruleus and subcoeruleus nuclei project to the pontine raphe complex, and the catecholamine cells in the lateral portion of the pontine catecholamine system project to the cerebellar cortex. The strong tendency for the catecholamine cell bodies to closely surround the brachium conjunctivum is unique in the cat.