Distribution of vasopressin and oxytocin cells and fibres in the hypothalamus of the domestic pig (Sus scrofa)

Abstract

The distribution of vasopressin and oxytocin cells and fibres was studied in the pig hypothalamus by means of monoclonal antibodies, in order to prevent the non-specific staining that is characteristic for the pig. The nucleus circularis is described for the first time in the pig hypothalamus and consists of both oxytocin and vasopressin containing cell bodies. A cell group, characteristic for the pig and horse, lateral and caudal from the vascular organ of the lamina terminalis, was found to be continuous with the supraoptic nucleus. It contained only oxytocin and it is proposed that this group be called pars dorsomedialis of the supraoptic nucleus. In this study, vasopressin has been demonstrated for the first time in the suprachiasmatic nucleus of the pig. The discussion focusses on how our findings in the pig differ from vasopressin and oxytocin systems identified in other mammalian species.