LH Triggers Ovulation in the Menstrual Cycle

Steps:

• Recall the menstrual cycle phases: follicular phase prepares eggs, ovulation releases the egg, luteal phase supports potential pregnancy.
• Identify roles of pituitary hormones: FSH stimulates follicle growth in ovaries.
• Note the mid-cycle surge: LH peaks, causing the mature follicle to rupture and release the egg (ovulation).
• Confirm via biology: This LH surge is triggered by rising estrogen levels.

Why B is correct:

• Luteinizing hormone (LH) directly causes ovulation by inducing the breakdown of the follicle wall, as defined in reproductive endocrinology.

Why the others are wrong:

• A: FSH promotes follicle development and estrogen production but does not trigger egg release.
• C: Oestrogen thickens the uterine lining and provides feedback to stimulate LH but isn't the direct releaser.
• D: Progesterone maintains the uterine lining post-ovulation and prevents further egg release.

Final answer: B