A bone that is formed within the mesenchyme is called

Options

A. Endochondral bone
B. Replacing bone
C. Sesamoid bone
D. Dermal bone

Answer

To answer the question "A bone that is formed within the mesenchyme is called," we need to analyze the options provided and understand the processes of bone formation.

### Step-by-Step Solution:

1. **Understanding Mesenchyme**: Mesenchyme is a type of connective tissue that is the precursor to various types of tissues, including bone. Bones can develop from mesenchymal cells through different ossification processes.

2. **Identifying Ossification Processes**: There are two main types of ossification:
- **Intramembranous Ossification**: This process involves the direct conversion of mesenchymal tissue into bone. It is responsible for the formation of flat bones, such as those in the skull and mandible.
- **Endochondral Ossification**: This process involves the formation of bone from a cartilage model. Most of the long bones in the body develop through this process.

3. **Evaluating the Options**:
- **Endochondral Bone**: This is formed through endochondral ossification, which does not originate from mesenchyme directly but rather from cartilage.
- **Replacing Bone**: This term generally refers to bones that replace cartilage but is not specific to mesenchymal origin.
- **Sesamoid Bone**: These bones develop within tendons and ligaments, derived from connective tissue, but not specifically from mesenchyme.
- **Dermal Bone**: This type of bone is formed directly from mesenchymal tissue through intramembranous ossification.

4. **Conclusion**: Since the question specifically asks for a bone that is formed within the mesenchyme, the correct answer is **dermal bone**. Dermal bones are formed from mesenchymal cells via intramembranous ossification.

### Final Answer:
A bone that is formed within the mesenchyme is called **dermal bone**.

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