Which structure receives releasing hormones from the hypothalamus via portal circulation to regulate endocrine function?

• A. Thalamus
• B. Hypothalamus
• C. Pituitary Gland
• D. Pineal Gland

Answer: (C)

Releasing or inhibiting hormones produced by the hypothalamus are delivered to regulate endocrine function through the hypothalamic-pituitary portal system. This specialized network sends these hypothalamic signals directly to the anterior pituitary (adenohypophysis) via portal veins, ensuring high local concentrations that control the secretion of pituitary trophic hormones such as ACTH, TSH, LH/FSH, growth hormone, and prolactin. In turn, these pituitary hormones regulate other endocrine glands throughout the body.

The posterior pituitary isn’t the target of releasing hormones via portal circulation; it receives neurohormones produced in the hypothalamus and released from axon terminals into the bloodstream.