Which hormone from the anterior pituitary triggers ovulation?

• A. FSH
• B. LH
• C. ACTH
• D. TSH

Answer: (B)

Ovulation is triggered by a surge of luteinizing hormone from the anterior pituitary. While follicle-stimulating hormone promotes growth of the ovarian follicles, it is the midcycle LH peak that causes the dominant follicle to rupture and release the oocyte. This LH surge happens as rising estrogen from the maturing follicle shifts from negative to positive feedback on the pituitary around midcycle. After ovulation, LH supports the formation of the corpus luteum, which then secretes progesterone to prepare the uterine lining for potential implantation. The other hormones listed don’t drive ovulation—ACTH stimulates the adrenal cortex, and TSH stimulates the thyroid.