Interstital cells renew

Options

A. all the cells of Hydra
B. a few cells of Hydra
C. a large number of cells of Hydra
D. they do not renew cells.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the renewing capability of interstitial cells in Hydra. We need to determine what these cells can renew.

2. **Identifying the Organism**: Hydra belongs to the phylum Cnidaria (previously referred to as Coelenterata). It is important to note that Hydra exhibits a diploblastic organization, meaning it has two germ layers: ectoderm and endoderm.

3. **Defining Interstitial Cells**: Interstitial cells are found between the epithelial and muscular cells in both the epidermis and gastrodermis of Hydra. These cells are characterized as round or oval and are undifferentiated.

4. **Function of Interstitial Cells**: These interstitial cells are often referred to as "embryonic reserves" because they have the ability to regenerate or repair tissues. They can differentiate into various types of cells, which is crucial for the organism's ability to recover from damage.

5. **Evaluating the Options**:
- **Option 1**: All the cells of Hydra - This option suggests that interstitial cells can renew into every type of cell in Hydra, which aligns with their totipotent nature.
- **Option 2**: A few cells of Hydra - This option implies limited renewal, which contradicts the function of interstitial cells.
- **Option 3**: A large number of cells of Hydra - While this suggests a significant renewal capability, it does not encompass the totality of cell types.
- **Option 4**: They do not renew the cells - This option is incorrect as interstitial cells are known for their regenerative abilities.

6. **Conclusion**: Based on the functions and characteristics of interstitial cells, the correct answer is **Option 1: All the cells of Hydra**. This is because interstitial cells can differentiate into any type of cell needed for the organism's repair and regeneration.