How do hypothalamic releasing hormones reach the anterior pituitary gland?

Hypothalamic releasing hormones reach the anterior pituitary gland through a specialized vascular network known as the hypophyseal-portal system.

The process functions as follows:

• Secretion: Neurosecretory cells located in the hypothalamus produce releasing hormones and discharge them into a capillary network within the median eminence, a region at the base of the brain.123
• Transport: These capillaries merge to form portal veins that traverse the pituitary stalk, directing the blood—and the hormones contained within it—directly into the microvasculature of the anterior pituitary gland.142
• Action: Once they reach the anterior pituitary, these hormones interact with specific target cells to stimulate or inhibit the secretion of pituitary hormones.123

This portal circulation is a critical mechanism that allows the central nervous system to regulate endocrine function by delivering neurohormones directly to the anterior pituitary, largely bypassing the general systemic circulation.423