The dioptrical region of eye of cockroach is constituted by 

Options

A. cornea and crystalline cone
B. cornea and cornaegen cells
C. vitrillae and cone cells
D. retinulae and crystalline cone

Answer

To answer the question regarding the dioptrical region of the eye of a cockroach, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure of Cockroach Eyes**:
- The eyes of a cockroach are compound eyes made up of multiple units called omatidia. Each omatidium contains photoreceptor cells that help in vision.

2. **Identifying the Dioptrical Region**:
- The dioptrical region of the eye is responsible for focusing light. In cockroaches, this region includes specific structures that aid in this function.

3. **Examining the Options**:
- **Option A**: Cornea and crystalline cone
- **Option B**: Cornea and corneogen cells
- **Option C**: Vitrella and cone cells
- **Option D**: Retinolai and crystalline cones

4. **Analyzing Each Option**:
- **Option A**: The cornea is a transparent layer that covers the eye, and the crystalline cone is a structure that helps in focusing light. Both are present in the dioptrical region.
- **Option B**: While the cornea is present, corneogen cells are not specifically known to constitute the dioptrical region.
- **Option C**: Vitrella is not part of the dioptrical region; it is associated with ocelli, which are simple eyes.
- **Option D**: Retinolai is not a recognized structure in the context of the dioptrical region of cockroach eyes.

5. **Conclusion**:
- Based on the analysis, the correct answer is **Option A: Cornea and crystalline cone**. This combination constitutes the dioptrical region of the cockroach eye.