Vascular and excretory organs are formed from

Options

A. Endoderm
B. Mesoderm
C. Ectoderm of embryonic disc.
D. Mesendoderm.

Answer

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks about the embryonic layer from which vascular and excretory organs are formed.

2. **Understand the Types of Embryonic Layers**: There are three primary germ layers in embryonic development:
- **Ectoderm**: This layer forms structures such as the skin and nervous system.
- **Mesoderm**: This layer gives rise to the circulatory system, muscles, bones, and excretory organs.
- **Endoderm**: This layer primarily forms the gastrointestinal tract and associated organs.

3. **Analyze the Options**:
- **A. Endoderm**: This is incorrect as it mainly forms the digestive system and associated organs.
- **B. Mesoderm**: This is the correct answer as it is responsible for forming the vascular system (heart and blood vessels) and excretory organs (kidneys).
- **C. Ectoderm**: This is incorrect as it forms the skin and nervous system, not vascular or excretory organs.
- **D. Mesoendoderm**: This term is not commonly used in embryology and does not specifically refer to a layer that forms vascular or excretory organs.

4. **Conclusion**: Based on the analysis, the vascular and excretory organs are formed from the **mesoderm**.

5. **Final Answer**: The correct option is **B. Mesoderm**.

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