Oestrogens stimulate the proliferation of the endometrium of the uterine wall during

Options

A. menstrual phase
B. follicular phase
C. luteal phase
D. ovulatory phase

Answer

To answer the question "Oestrogens stimulate the proliferation of the endometrium of the uterine wall during," we need to analyze the menstrual cycle and the role of hormones during its different phases.

### Step-by-Step Solution:

1. **Understanding the Menstrual Cycle**:
- The menstrual cycle consists of several phases: menstrual phase, follicular phase, ovulatory phase, and luteal phase.
- Each phase is characterized by specific hormonal changes and physiological events in the female reproductive system.

2. **Menstrual Phase**:
- This is the first phase of the cycle where menstruation occurs due to the breakdown of the endometrial lining.
- It lasts for about 3 to 5 days and occurs when the released ovum is not fertilized.

3. **Follicular Phase**:
- Following the menstrual phase, the follicular phase begins.
- During this phase, primary follicles in the ovaries start to grow and develop into mature Graafian follicles.
- Simultaneously, the endometrium of the uterus begins to regenerate and proliferate.

4. **Role of Oestrogens**:
- The growth of the Graafian follicles is accompanied by the secretion of oestrogens.
- Oestrogens are crucial as they stimulate the proliferation of the endometrial lining in preparation for a potential pregnancy.

5. **Ovulatory Phase**:
- This phase occurs when the mature follicle ruptures and releases an ovum, triggered by a surge in luteinizing hormone (LH).
- While this phase is important for ovulation, it is not primarily responsible for the proliferation of the endometrium.

6. **Luteal Phase**:
- After ovulation, the luteal phase begins, where the remnants of the Graafian follicle transform into the corpus luteum, which secretes progesterone.
- Progesterone is essential for maintaining the endometrium but does not stimulate its proliferation.

7. **Conclusion**:
- The proliferation of the endometrium due to oestrogens occurs specifically during the follicular phase of the menstrual cycle.

### Final Answer:
Oestrogens stimulate the proliferation of the endometrium of the uterine wall during the **follicular phase**.

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