Level of estrogen and progesterone are minimum at the time of
(a) Folicular phase
(b) Ovulation
(c) Secretory phase
(d) Onset of menstrual phase

Options

A. Folicular phase
B. Ovulation
C. Secretory phase
D. Onset of menstrual phase.

Answer

To determine when the levels of estrogen and progesterone are at their minimum, let’s analyze each option step by step:

1. **Understanding Hormone Production**:
- Estrogen and progesterone are primarily produced by the corpus luteum, which forms after ovulation.
- The levels of these hormones fluctuate throughout the menstrual cycle.

2. **Analyzing Each Phase**:
- **(a) Follicular Phase**: This phase occurs after menstruation and before ovulation. During this phase, estrogen levels begin to rise as follicles develop, while progesterone levels remain low. Therefore, levels are not at their minimum here.
- **(b) Ovulation**: This is the phase where a surge in luteinizing hormone (LH) occurs, leading to ovulation. Estrogen levels peak just before ovulation, and progesterone is still low. Thus, this is not the time of minimum levels.
- **(c) Secretory Phase**: This phase follows ovulation and is characterized by the presence of the corpus luteum, which secretes high levels of progesterone and estrogen to prepare the endometrium for potential implantation. Therefore, hormone levels are not at their minimum during this phase.
- **(d) Onset of Menstrual Phase**: This is the phase where the corpus luteum degenerates if fertilization does not occur, leading to a sharp decline in both estrogen and progesterone levels. This is the time when the levels of these hormones are at their lowest.

3. **Conclusion**: Based on the analysis, the correct answer is **(d) Onset of menstrual phase** as this is when the levels of estrogen and progesterone are at their minimum.

**Final Answer**: (d) Onset of menstrual phase

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