Vasopressin and oxytocin immunoreactive neurons and fibers in the forebrain of male and female common marmosets (Callithrix jacchus)

Vasopressin (AVP) and oxytocin (OT) immunoreactive (ir) neurons and fibers were examined in the forebrain of male and female common marmosets (Callithrix jacchus). As expected from previous studies of cell distribution in the rodent and primate brain, AVP-ir cells were most evident in the paraventricularis, supraopticus, and suprachiasmaticus of the hypothalamus. AVP-ir cells were also widely distributed in the lateral hypothalamus and the bed nucleus of the stria terminalis. A sexually dimorphic pattern of AVP-ir cells was found in the bed nucleus of the stria terminalis, in which males had more AVP-ir cells than females. OT-ir cells were found in the paraventricularis and supraopticus of the hypothalamus as well as in the bed nucleus of the stria terminalis and the medial amygdala. Male and female marmosets did not differ in the distribution of OT-ir cells. Fibers for both AVP and OT were evident outside of the hypothalamic-neurohypophyseal tract, but a plexus of AVP-ir fibers in the lateral septum or lateral habenular nucleus, as seen in the rat brain, could not be detected for either peptide.