supraopticohypophysial tract

su·pra·op·ti·co·hy·po·phy·si·al tract

[TA]
a bundle of unmyelinated fibers originating from all cells of the supraoptic nucleus and an estimated 20% of those of the paraventricular nucleus of the hypothalamus, which extend through the infundibulum and pituitary stalk to their endings in the posterior lobe of the hypophysis; the fibers convey neurosecretory substances, vasopressin and oxytocin, which are stored in (and can be released into the circulating blood from) their terminals.
See also: pituitary gland, neurosecretion.