A typical angiosperm embryosac at maturity is :-

Options

A. 7 celled - 8 nucleated
B. 9celled- 7 nucleated
C. 3 celled - 3 nucleated
D. 2celled- 2 nucleated

Answer

To determine the characteristics of a typical angiosperm embryo sac at maturity, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Structure**: The angiosperm embryo sac, also known as the female gametophyte, develops from the megaspore mother cell (megasporangium) through a series of mitotic divisions.

2. **Mitosis of Megaspore**: The megaspore mother cell undergoes mitotic divisions. Specifically, it divides three times (four total divisions) to produce a total of eight nuclei.

3. **Formation of Cells**: Although eight nuclei are formed, not all of them become separate cells. Instead, two of these nuclei remain in the center of the embryo sac without undergoing cytokinesis, which means they do not split into separate cells.

4. **Cell Arrangement**: The arrangement of the cells in the mature embryo sac is as follows:
- **Polar Nuclei**: The two nuclei that do not undergo cytokinesis form a single cell known as the central cell (or polar nuclei).
- **Antipodal Cells**: Three of the cells migrate to one end of the embryo sac and form the antipodal cells.
- **Synergids and Egg Cell**: Two cells move to the opposite end and form the synergids, and one of the cells is the egg cell.

5. **Counting Cells and Nuclei**:
- Total cells: 7 (1 central cell with 2 nuclei + 3 antipodal cells + 2 synergids + 1 egg cell).
- Total nuclei: 8 (the central cell has 2 nuclei, and the other 5 cells each have 1 nucleus).

6. **Conclusion**: Therefore, a typical angiosperm embryo sac at maturity is characterized as having 7 cells and 8 nuclei.

### Final Answer:
A typical angiosperm embryo sac at maturity is **7-celled and 8-nucleated**.

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