[TA] the upward extension of the anterior lobe of the pituitary gland that wraps around the infundibular stalk; its cells, mostly gonadotropic, are arranged in cords and clusters; it is supplied by the superior hypophysial arteries and contains the first (primary) capillary bed and the venules of a portal system that carries neurosecretory factors from the hypothalamus to a second (secondary) capillary bed in the adenohypophysis, where these factors regulate the release of hormones.pituitary gland. SYN: infundibular part, pars infundibularis.