Hypophyseal portal system

Releasing factors secreted from neurons in (ventromedial and dorsomedial) nuclei from the middle part of the hypothalamus are responsible for activation or inhibition of endocrine cells within the adenohypophysis. These are released into capillaries (derived from the superior hypophyseal artery) draining into small veins along the infundibulum. The veins, in turn, break up into a second capillary bed within the adenohypophysis. This vasculature is termed the hypothalamo-hypophyseal portal venous system also known by its abbreviation, the hypophyseal portal system.

The arterial supply of the base of the infundibulum (and of the adenohypophysis) is from the superior hypophyseal artery, a branch of the cerebral part of the internal carotid artery. The venous drainage of the adenohypophysis is via the hypophyseal vein into the cavernous sinus.