Demonstration of a new dopamine-containing cell group in the primate rostral telencephalon.

The presence of dopaminergic neurons in the rostral forebrain has long been uncertain though the existence of tyrosine-hydroxylase (TH)-containing cells has been known in the region. Using an antibody to dopamine (DA), we demonstrated neurons immunoreactive (ir) to DA in the rostroventral striatum of the Japanese monkey (Macaca fuscata). The DA-ir cells were found at the ventral margin of the rostral part of the caudate nucleus, at the ventral margin of the rostral part of the nucleus accumbens, in the olfactory tubercle, and along the lateral margin of the putamen. These cells were intensely stained, small in size, and fusiform or ovoid in shape, and had one or two short processes. DA-ir cells were far smaller in number than TH-ir ones. The primates may possess a unique dopaminergic system in the rostral telencephalon.