In the human female menstrual cycle, what endocrine event directly triggers ovulation approximately 24 to 36 hours later?
Answer and explanation
Correct answer: B. A surge in Luteinizing Hormone (LH) stimulated by high estrogen feedback
- Step 1: In the late follicular phase, sustained high estradiol levels from the dominant follicle switch estrogen feedback from negative to positive. Step 2. This triggers the LH surge from the anterior pituitary, which induces follicular rupture and oocyte release. Answer: A surge in Luteinizing Hormone (LH) stimulated by high estrogen feedback. Why not the others: Progesterone drops during menstruation; hCG is secreted after implantation.
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