How many cells and nucleus are present in a developed embryo sac

Answer

To determine the number of cells and nuclei present in a developed embryo sac, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Origin of the Embryo Sac**:
- The embryo sac develops from a megasporangium, which is also known as the ovule. The initial cell is the megaspor mother cell (MMC), which is diploid (2N).

2. **Meiosis in the Megaspor Mother Cell**:
- The MMC undergoes meiosis to produce four haploid megaspores. Typically, three of these megaspores degenerate, leaving one functional megaspore.

3. **Development of the Embryo Sac**:
- The surviving megaspore undergoes three rounds of mitotic divisions:
- The first mitotic division produces two nuclei.
- The second mitotic division produces four nuclei.
- The third mitotic division produces a total of eight nuclei.

4. **Cell Arrangement in the Embryo Sac**:
- These eight nuclei are arranged into seven cells:
- At the chalazal end, there are three antipodal cells.
- In the middle, there is one egg cell and two synergids, collectively known as the egg apparatus.

5. **Final Count**:
- Therefore, in a developed embryo sac, there are **7 cells** and **8 nuclei**.

### Summary:
- **Number of Cells**: 7
- **Number of Nuclei**: 8