Fractured bones can be rejoined by the reactivation of  

Options

A. osteoblasts
B. osteoclasts
C. osteocytes
D. all the above

Answer

To solve the question "Fractured bones can be rejoined by the reactivation of," we need to analyze the options provided and understand the roles of the different types of bone cells mentioned.

### Step-by-Step Solution:

1. **Understanding Bone Cells**:
- There are three main types of bone cells: osteoblasts, osteoclasts, and osteocytes. Each has a specific function in bone health and maintenance.

2. **Osteoblasts**:
- Osteoblasts are specialized mesenchymal cells responsible for synthesizing bone matrix. They play a crucial role in the formation of new bone and the mineralization process. When a bone is fractured, osteoblasts are activated to produce new bone tissue and help in the healing process.

3. **Osteoclasts**:
- Osteoclasts are cells that break down bone tissue. They are involved in the resorption of bone, which is important for the maintenance and remodeling of bones. However, they do not help in rejoining fractured bones; instead, they are involved in the degradation of bone.

4. **Osteocytes**:
- Osteocytes are mature bone cells that maintain bone tissue. They are formed from osteoblasts that have become trapped in the matrix they secreted. While they play a role in bone health, they do not directly contribute to the rejoining of fractured bones.

5. **Conclusion**:
- Given the roles of these cells, the correct answer to the question is that fractured bones can be rejoined by the reactivation of **osteoblasts**. They are the cells that synthesize new bone matrix and facilitate the healing process after a fracture.

### Final Answer:
Fractured bones can be rejoined by the reactivation of **osteoblasts**.

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