Morphological Characteristics of C1 and C2 Adrenergic Neurone Groups in Marmoset Monkey Brainstem by using Antibody against Phenylethanolamine-N-methyltransferase

Summary This work describes a mapping study of phenylethanolamine‐N‐methyltransferase (PNMT) immunoreactive neurones and fibres in the medulla oblongata of the marmoset monkey, Callithrix jacchus. Two groups of PNMT‐immunoreactive neurones were found in the marmoset monkey medulla oblongata: a ventrolateral (C1 group) and a dorsomedial PNMT‐immunoreactive cells group (C2 group). The PNMT‐immunoreactive cells in the ventrolateral group C1 were found to be located around the lateral reticular nucleus. The PNMT‐immunoreactive somata within the ventrolateral medulla are round to oval, and mostly multipolar with branched processes. In the dorsomedial group C2, PNMT‐immunoreactive cell bodies appeared near the obex. The majority of the dorsomedial PNMT‐immunoreactive neurones were observed in the nucleus tractus solitarius; although some were present in the dorsal motor nucleus of the vagus. The PNMT‐immunoreactive somata in the dorsomedial medulla were small and round or ovoid. These results provide information upon the adrenergic system in the medulla oblongata of a species that presents a useful model of a small primate brain, the marmoset monkey.