Which of the following changes does not occur during conversions of secondary follicle into tertiary follicle?

Options

A. Development of antrum.
B. Differentiation of theca layers.
C. Primary oocyte completes meiosis-l.
D. Second polar body is released.

Answer

To solve the question, "Which of the following changes does not occur during the conversions of secondary follicle into tertiary follicle?", we need to analyze each of the provided options regarding the changes that occur during this conversion.

### Step-by-Step Solution:

1. **Understanding Follicle Development**:
- The ovarian follicles develop through several stages: primordial, primary, secondary, and tertiary (or Graafian) follicles. Each stage involves specific changes.

2. **Option Analysis**:
- **Option 1: Development of Antrum**:
- During the conversion from secondary to tertiary follicle, an antrum (a fluid-filled cavity) develops. This is a key feature of tertiary follicles.
- **Conclusion**: This change occurs.

- **Option 2: Differentiation of Theca Layers**:
- The secondary follicle develops two layers of theca: theca interna and theca externa. This differentiation is crucial for the tertiary follicle.
- **Conclusion**: This change occurs.

- **Option 3: Primary Oocyte Completes Meiosis I**:
- As the secondary follicle matures into a tertiary follicle, the primary oocyte completes meiosis I, resulting in a secondary oocyte and a first polar body.
- **Conclusion**: This change occurs.

- **Option 4: Second Polar Body is Released**:
- The second polar body is produced after the completion of meiosis II, which occurs only after fertilization. This means that during the conversion from secondary to tertiary follicle, the second polar body is not released.
- **Conclusion**: This change does not occur.

3. **Final Answer**:
- The correct answer is **Option 4: Second polar body is released**.