In human physiology, what is the primary action of luteinizing hormone (LH)?

• A. It stimulates milk production in the mammary glands.
• B. It triggers ovulation and stimulates the formation of the corpus luteum in females, and stimulates testosterone production by Leydig cells in males.
• C. It increases water reabsorption in the kidney collecting ducts.
• D. It stimulates growth of ovarian follicles and promotes estrogen production by granulosa cells.

Answer: (B)

Verified step by step guidance

1. Identify the hormone in question: luteinizing hormone (LH), which is a key hormone in the reproductive system.
2. Recall the primary functions of LH in females: it triggers ovulation, which is the release of an egg from the ovary, and it stimulates the formation of the corpus luteum, a structure that produces progesterone to support pregnancy.
3. Recall the primary functions of LH in males: it stimulates Leydig cells in the testes to produce testosterone, which is essential for male secondary sexual characteristics and spermatogenesis.
4. Compare these functions with the other options given: milk production is stimulated by prolactin, water reabsorption in kidneys is regulated by antidiuretic hormone (ADH), and growth of ovarian follicles with estrogen production is primarily stimulated by follicle-stimulating hormone (FSH).
5. Conclude that the primary action of LH is related to ovulation and corpus luteum formation in females, and testosterone production in males.