AbstractSpecific, fluorescent, subependymal perikarya were found in thepars anteriorof the paraventricular organ (PVOpa), in thenucleus recessus lateralis(NRL) and in thenucleus recessus posterioris(NRP). No fluorescent perikarya were present in thenucleus lateralis tuberis(NLT). Fluorescent nerve tracts connect the PVOpa and the NRL with the NRP, and interconnect the paired NRP. Thenucleus preopticus(NPO) and the NLT receive a large input of aminergic nerve fibers. The monoaminergic nuclei are well vascularized, and their vascular plexes seem to be connected. A capillary plexus is situated dorsal to the NRP and exhibits no contact with the pituitary. It is surrounded by the prominent fluorescent tracts connecting the aminergic nuclei.