Question

Which one of the following hormones is at its peak during ovulation?

• A. Progesterone
• B. Estrogen
• C. Luteinising hormone
• D. Follicle stimulating hormone

Hint:

Menstrual Cycle Hormone Peaks:
$\bullet$ Day 14 (Ovulation): Peak LH (LH surge $\rightarrow$ follicle rupture) and peak FSH.
$\bullet$ Late Follicular Phase: Peak Estrogen.
$\bullet$ Mid-Luteal Phase (Day 21--22): Peak Progesterone (secreted by Corpus Luteum).

Answer 1

The Correct Option is C

Concept:
The human menstrual cycle is regulated by gonadotropins (LH and FSH) from the anterior pituitary and ovarian steroids (estrogen and progesterone).

Step 1: Hormonal Dynamics during Ovulation (Mid-cycle, $\sim$14th Day):
During the proliferative (follicular) phase, growing ovarian follicles secrete estrogen. High levels of estrogen exert positive feedback on the pituitary gland.
Around the midpoint of the 28-day menstrual cycle (day 14), both LH and FSH attain peak secretion levels.
The rapid, dramatic surge in Luteinising Hormone (LH) concentration—commonly known as the LH surge—reaches its maximum peak.
This LH surge induces the rupture of the mature Graafian follicle, leading to the release of the secondary oocyte into the peritoneal cavity (ovulation).

Step 2: Evaluating the Other Hormones:
- Progesterone: Remains low during the follicular and ovulatory phases; it reaches its peak later, during the luteal (secretory) phase when secreted by the corpus luteum.
- Estrogen: Peaks just prior to ovulation, but the sharpest physiological peak directly causing ovulation is the LH surge.
- Luteinising Hormone (LH): The definitive hormone whose mid-cycle surge and maximal peak trigger ovulation.

Step 3: Final Selection:
Therefore, the hormone at its decisive peak during ovulation is Luteinising hormone (Option C).