Which embryonic germ layer makes up the bulk of the future human body ?

Options

A. ectoderm
B. endoderm
C. mesoderm
D. decidua

Answer

**Step-by-Step Solution:**

1. **Understanding Embryonic Germ Layers**: The human body develops from three primary embryonic germ layers: ectoderm, mesoderm, and endoderm. Each layer has distinct roles in forming different tissues and organs.

2. **Identifying the Layers**:
- **Ectoderm**: This is the outermost layer. It primarily forms structures such as the skin, hair, nails, and the nervous system.
- **Endoderm**: This is the innermost layer. It forms the lining of the digestive tract and other internal organs, but it does not contribute significantly to the bulk of the body.
- **Mesoderm**: This is the middle layer. It is responsible for forming most of the body's structures, including muscles, bones, the circulatory system, and other organs.

3. **Determining the Bulk of the Body**: Among the three layers, the mesoderm is the layer that contributes the most to the formation of the body’s organs and systems. It is composed of a denser concentration of cells that develop into various tissues.

4. **Conclusion**: Therefore, the embryonic germ layer that makes up the bulk of the future human body is the **mesoderm**.

**Final Answer**: Mesoderm

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