The cytoarchitecture of the interfascicular nucleus and ventral tegmental area of tsai in the rat

Abstract

The cytoarchitecture of the ventral tegmental area of Tsai (VTA) has been studied in detail in the rat with the aid of both conventional techniques and glyoxylic acid-fluorescence histochemistry. Three main dopamine containing cells groups can be distinguished: nucleus paranigralis, nucleus parabrachialis pigmentosus lies dorsally, and nucleus paranigralis ventrally in the VTA, while nucleus linearis continues posteriorly and medially from VTA and extends dorsally in the midline up towards the dorsal raphe nucleus. Fluorescent neurons in these three groups correspond to the A10 group. In addition to these previously described findings, the present study shows evidence for a further small but cytoarchitecturally distinct dopaminergic group called the interfascicular nucleus. This lies anterorly and ventrally in the ventral tegmentum in the midline, dorsal to the rostral portion of the interpeduncular nucleus and interpeduncular fossa. The significance of these cytoarchitectural findings in discussed in relation to the known connections of the region.