Vascular and neural connections between the hypothalamus and pituitary

Schematic representation of the vascular and neural connections of the hypothalamic-pituitary axis. The paraventricular nucleus neurons have terminals in the median eminence where their hormones are released directly into the primary capillary plexus, traverse the long portal veins in the pituitary stalk, and enter the secondary plexus in the anterior pituitary gland. The primary plexus, long portal venous system, and secondary plexus comprise the hypothalamic-hypophyseal portal venous system. In contrast, the axons of the supraoptic nucleus travel down the supraopticohypophyseal tract and release vasopressin and oxytocin directly in the posterior pituitary.