Monoamine distribution in primate brain—IV. Indoleamine-containing perikarya in the brain stem of Macaca arctoides

Abstract The histochemical fluorescence technique for the demonstration of monoamines in the central nervous system was employed to assess the distribution of serotonin-containing neurons within the brain stem of the immature and adult stump-tailed macaque ( Macaco arctoides ). Microspectrofluorometric analysis was performed in order to verify the existence of serotonin within perikarya which contained yellow histofluorescence. Serotonin-containing perikarya were found within raphe nuclei including nucleus raphe-pallidus, -obscurus, -pontis, -magnus, -dorsalis, and -centralis superioralis. Serotoninergic perikarya did not appear confined exclusively to the raphe, but were observed in the reticular formation and other brain stem nuclei including the locus coeruleus and nucleus subcoeruleus. Serotoninergic cells were not seen within the brain stem at superior collicular levels. The localization of Serotoninergic perikarya in regions other than the raphe nuclei presents certain dissimilarities in relation to patterns reported in other mammalian species.