Distributional pattern of oxytocin- and vasopressin-immunoreactivity in the neurohypophysis of the Djungarian hamster (Phodopus sungorus).

The topography of oxytocin (OT)- and vasopressin (VP)-containing axons of the hypothalamo-neurohypophyseal system was studied in the neurohypophysis of the Djungarian hamster (Phodopus sungorus) by means of immunohistochemistry. Compared with other mammalian species, the neurohypophysis of Phodopus shows some peculiarities. Accumulations of OT-immunoreactivity around the distal vessels of the primary portal plexus can be observed in the distal median eminence and neural stem. This staining pattern indicates that OT is secreted into portal blood. In the neural lobe, OT- and VP-immunopositive fibers terminate in different areas. The vast majority of the OT-containing axons is distributed in the dorsal part of the neural lobe. In contrast, VP-containing axons are mainly found in the centre of the neural lobe up to the pars intermedia.