Wall of a pollen sac consists of

Options

A. Endothecium and tapetum
B. tapetum and middle layers
C. Endothecium, middle layers and tapetum
D. Epidermis, endothecium, middle layers and tapetum.

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Structure of Pollen Sac:**
- The pollen sac, also known as microsporangium, is a crucial part of the male reproductive structure in flowering plants. It is responsible for producing and storing pollen grains.

2. **Identifying the Layers of the Pollen Sac:**
- The wall of the pollen sac consists of several distinct layers. Each layer has specific functions and characteristics.

3. **First Layer - Epidermis:**
- The outermost layer of the pollen sac is the epidermis.
- It is a unilayered structure that serves a protective function.

4. **Second Layer - Endothecium:**
- Beneath the epidermis lies the endothecium.
- This layer consists of elongated cells that develop fibrous thickening.
- The endothecium aids in the dispersal of microspores.

5. **Third Layer - Middle Layer:**
- Below the endothecium is the middle layer, which is made up of 2 to 4 layers of flattened cells.
- This layer is collectively referred to as the middle cells and serves to store reserve food material during the early stages of microspore development.

6. **Innermost Layer - Tapetum:**
- The innermost layer of the pollen sac is the tapetum.
- It consists of radially elongated cells and is responsible for providing nutrition to the developing pollen grains.

7. **Conclusion:**
- The wall of a pollen sac consists of four main layers: epidermis, endothecium, middle layer, and tapetum.

**Final Answer:**
The wall of a pollen sac consists of the epidermis, endothecium, middle layer, and tapetum.

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