In anther wall, which of the following constitutes third layer from outside?

Options

A. Endothecium
B. Endothelium
C. Aleurone layer
D. Middle layers

Answer

To determine which layer constitutes the third layer from the outside in the anther wall, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Layers of the Anther Wall**:
The anther wall is composed of four distinct layers that surround the microsporangium.

2. **List the Layers from Outermost to Innermost**:
- **First Layer (Outermost)**: Epithelium (or Epithelial Layer) - This is a protective single layer.
- **Second Layer**: Endothelium - This layer consists of radially elongated cells and helps in the dehiscence of the anther at maturity.
- **Third Layer**: Middle Layers - This consists of 3 to 4 layers of thin-walled cells that may contain starch and other reserve materials.
- **Fourth Layer (Innermost)**: Tapetum - This layer surrounds the sporogenous tissue and is rich in nuclei and dense cytoplasm.

3. **Determine the Third Layer**:
From the above listing, the third layer from the outside is the **Middle Layers**.

### Final Answer:
The third layer from the outside in the anther wall is the **Middle Layers**.

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