Immature bone cells that secrete collagen fibres and cause mineralization of bone are 

Options

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

Answer

To solve the question regarding immature bone cells that secrete collagen fibers and cause mineralization of bone, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Bone Cells**:
- Bone tissue consists of various types of cells, including osteoblasts, osteocytes, and osteoclasts. Each type has a specific function in bone formation and maintenance.

2. **Identifying the Functions of Each Cell Type**:
- **Osteoclasts**: These are large cells that break down bone tissue (bone resorption). They are not involved in the secretion of collagen fibers or mineralization.
- **Osteocytes**: These are mature bone cells that originate from osteoblasts. They are involved in maintaining bone tissue but do not secrete collagen or cause mineralization.
- **Osteoblasts**: These are immature bone cells responsible for synthesizing the bone matrix, which includes the secretion of collagen fibers. They also play a crucial role in the mineralization process of bones.

3. **Conclusion**:
- Based on the functions of the cells, the correct answer to the question is **osteoblasts**. They are the cells that secrete collagen fibers and are responsible for the mineralization of bone.

### Final Answer:
The immature bone cells that secrete collagen fibers and cause mineralization of bone are **osteoblasts**.

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