Middle layers of the microsporangial wall

Options

A. Shrivel at maturity of anther
B. Persist but remain thin-walled
C. Degenerate before maturity
D. Persist and become thickened.

Answer

To answer the question regarding the middle layers of the microsporangial wall, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of Microsporangium**:
- The microsporangium, also known as pollen sac, consists of several layers including the epidermis, middle layer, and tapetum.

2. **Identify the Role of the Middle Layer**:
- The middle layer of the microsporangial wall is generally ephemeral, meaning it has a short lifespan.

3. **Observe Changes During Development**:
- As the microsporangium matures, the cells of the middle layer undergo changes. They typically become flattened and may get crushed during the process of meiosis, which occurs in pollen mother cells.

4. **Consider Exceptions**:
- While the middle layer usually degenerates before maturity, there are exceptions. In some plants like Lilium and Ranunculus, the middle layers may persist even after maturity.

5. **Conclude the Correct Option**:
- Based on the information, the most accurate statement regarding the middle layer of the microsporangial wall is that it degenerates before maturity, which leads us to select the correct option.

### Final Answer:
The correct option is that the middle layer of the microsporangial wall degenerates before maturity.

---