With a neat, labelled diagram, describe the parts of a mature angiosperm embryo sac. Mention the role of synergids.

Explanation

### Step-by-Step Solution:

**Step 1: Introduction to the Embryo Sac**
The mature angiosperm embryo sac is the female gametophyte, which is crucial for sexual reproduction in flowering plants. It develops from a single functional megaspore after the process of megasporogenesis.

**Step 2: Megasporogenesis**
- **Definition**: Megasporogenesis is the formation of a functional megaspore from the megaspore mother cell through meiotic division.
- **Process**: The megaspore mother cell (diploid) undergoes meiosis, resulting in four haploid megaspores. Out of these, only one remains functional, while the other three degenerate.
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