Cornea and crystalline cone are secreted respectively by 

Options

A. cone cells, corneagen cells
B. lenticular cells, semper cells
C. semper cells, retinulae
D. retinulae and rhandomeres

Answer

To answer the question "Cornea and crystalline cone are secreted respectively by," we need to identify the correct cells responsible for secreting these structures in the eyes of the cockroach (Periplaneta americana).

### Step-by-Step Solution:

1. **Understanding the Structures**:
- The cornea and crystalline cone are parts of the compound eyes found in arthropods, particularly in cockroaches.
- The cornea is the outermost layer that protects the eye and helps in focusing light.
- The crystalline cone is a transparent structure that aids in directing light to the photoreceptor cells.

2. **Identifying the Cells**:
- The cornea is secreted by **lenticular cells**.
- The crystalline cone is secreted by **shemper cells**.

3. **Matching the Options**:
- Now, we need to match the identified cells with the options provided:
- **Option A**: Cone cells and corneogen cells
- **Option B**: Lenticular cells and shemper cells
- **Option C**: Shemper cells and retinule
- **Option D**: Retinule and the random years
- From our identification, we see that the correct pairing is **Lenticular cells (for cornea)** and **Shemper cells (for crystalline cone)**.

4. **Conclusion**:
- Therefore, the correct answer is **Option B: Lenticular cells and shemper cells**.