Final answer:
The hypophyseal portal system is what forms within the median eminence of the hypothalamus, facilitating transport of hormones directly to the anterior pituitary gland.
Step-by-step explanation:
The Hypophyseal Portal System
The structure that forms within the median eminence of the hypothalamus is the hypophyseal portal system. This system is crucial for neuroendocrine communication between the hypothalamus and the anterior pituitary gland. It begins with the superior hypophyseal artery, extends into the primary capillary plexus, through the portal veins, and reaches the anterior pituitary, where it influences hormone release.
The hypophyseal portal system allows hypothalamic hormones to reach the anterior pituitary without passing through the systemic circulation first. This direct connection ensures efficient regulation of hormone release, either stimulated by changes in the blood or by the nervous system. Hormones from the hypothalamus, known as releasing factors, travel through this portal system to the anterior pituitary which, in turn, secretes hormones that act on other endocrine glands and tissues.