The term premammillary nuclei refers to two groups of cells demonstrated by Nissl stain ventrally in the posterior hypothalamic region just rostral to the medial mammillary nucleus. They are the dorsal premammillary nucleus and the ventral premammillary nucleus.They are prominent in the rat ( Swanson-2004 ) and the mouse ( Hof-2000 ). Some authors report them also in the macaque ( Bleier-1984 ), though others indicate that they are represented only by a small group of cells in that species ( Crosby-1962; Paxinos-2009a ). They are not detectable by Nissl stain in the human ( Saper-2004 ). Functionally they are part of the behavior control column of the brainstem motor system ( Swanson-2004 ).