Q.The following is the illustration of the sequence of ovarian events (a-i) in a human female.

Step 1. Locate ovulation in the sequence. Panel F shows the follicle rupturing and releasing the egg — this is ovulation, the release of the oocyte from the mature Graafian follicle into the fallopian tube.

Step 2. Identify the stage of oogenesis it represents. The cell released at ovulation is not a fully matured ovum but a secondary oocyte, arrested in metaphase of meiosis-II; meiosis-II is completed (giving the true ovum/second polar body) only if the oocyte is fertilised.

Step 3. Name the hormones responsible. As the follicle (panels B–E) grows, its granulosa/theca cells secrete rising levels of estrogen. This rising estrogen feeds back on the hypothalamus-pituitary axis to trigger a sharp mid-cycle LH surge (along with a smaller FSH surge) from the anterior pituitary; the LH surge is the direct trigger that causes the Graafian follicle to rupture (panel F).

Step 4. Explain the simultaneous uterine changes. While the follicle is maturing and estrogen is rising, the endometrium of the uterus undergoes the proliferative (follicular) phase — its glands, stroma and blood supply regenerate and thicken — so that the lining is ready to receive and support an embryo if fertilisation occurs around the time of ovulation. …

Trace the labelled stages of the ovarian cycle in sequence, match each to its known follicular/luteal stage, and connect the hormo …

• Saying a fully mature ovum (rather than a secondary oocyte) is released at ovulation
• Attributing ovulation to FSH alone instead of the LH surge …