Based on cellular mechanisms there are two major types of regeneration found in the animals . Which one of the following is the correct example of the type mentioned?

Options

A. Epimorphosis - Regeneration of crushed and filtered out pieces of a Planaria into as many new Planarians.
B. Morphallaxis - Regeneration of two transversely cut equal pieces of a Hydra into two small hydras
C. Epimorphosis - Replacement of old and dead erythrocytes by the new ones.
D. Morphallaxis - Healing up of a wound in the skin.

Answer

To solve the question regarding the two major types of regeneration in animals based on cellular mechanisms, we will follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Regeneration**:
- Regeneration in animals can be classified into two main types based on cellular mechanisms: **Morpholaxis** and **Epimorphosis**.

2. **Define Morpholaxis**:
- Morpholaxis is a type of regeneration where the lost body parts are replaced through the remodeling of the remaining tissue. Importantly, there is minimal to no cellular proliferation involved in this process.

3. **Example of Morpholaxis**:
- A classic example of Morpholaxis is seen in **Hydra**. When a Hydra is cut into two pieces, each piece can regenerate into a new Hydra. The regenerated Hydras are smaller than the original but will grow to their full size over time.

4. **Define Epimorphosis**:
- Epimorphosis involves active cellular proliferation. In this type, there is a rapid multiplication of cells that occurs before the lost body parts are replaced.

5. **Example of Epimorphosis**:
- An example of Epimorphosis is found in **Planaria** (flatworms). When a Planarian is cut, stem cells called neoblasts proliferate and migrate to the injury site, forming a mass known as the regeneration blastema, which eventually differentiates into the necessary tissues.

6. **Analyze the Options**:
- The question provides options related to these types of regeneration. We need to identify which option correctly represents the type of regeneration described.

7. **Evaluate Each Option**:
- **Option 1**: Incorrect for Epimorphosis.
- **Option 2**: Correct for Morpholaxis (regeneration of two transversely cut equal pieces in two small hydras).
- **Option 3**: Incorrect as it does not represent either type.
- **Option 4**: Incorrect as it pertains to healing rather than regeneration.

8. **Conclusion**:
- Based on the definitions and examples analyzed, the correct answer is **Option 2**, which states that Morpholaxis is the regeneration of two transversely cut equal pieces in two small hydras.