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. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: Curr Opin Endocrinol Diabetes Obes. 2012 Jun;19(3):220–227. doi: 10.1097/MED.0b013e3283534b11

Figure 1.

Figure 1

Schematic feedback control of the human hypothalamic-pituitary-gonadal (HPG) axis. In males and females, kisspeptin-triggeredpulsatile secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the release of pituitary gonadotrophins (FSH and LH). FSH binds to its receptors located in testicular Sertoli and ovarian granulosa cells, and stimulates the secretion of inhibins that suppress FSH production from the pituitary. LH interacts with receptors on testicular Leydig cells and ovarian theca and granulosa cells, thereby stimulating the production of steroid hormones that stimulate their target cells in the reproductive tract.Steroid hormones (androgens, estrogens, progesterone) produced by ovaries and testesexert theirnegative (males) and negativeand positive (females)endocrine feedback to hypothalamic-pituitary levelby regulating thesynthesis and secretion of kisspeptin, GnRH and gonadotrophins.