Retina,eye lens brain and skin are formed from

Options

A. Mesoderm-skeleton
B. Ectoderm
C. Endoderm
D. Both ectoderm and endoderm.

Answer

To answer the question regarding the embryonic origin of the retina, eye lens, brain, and skin, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The options given are:
- A) Mesoderm
- B) Ectoderm
- C) Endoderm
- D) Both ectoderm and endoderm

2. **Understand the Germ Layers**:
- **Ectoderm**: This is the outermost layer of the embryo. It gives rise to structures such as the skin, hair, nails, and the entire nervous system, including the brain and sensory organs.
- **Mesoderm**: This is the middle layer. It forms muscles, bones, and the circulatory system.
- **Endoderm**: This is the innermost layer. It primarily develops into the gastrointestinal tract and associated organs.

3. **Analyze the Structures**:
- The retina and eye lens are parts of the eye, which is derived from the ectoderm.
- The brain is part of the central nervous system, also derived from the ectoderm.
- The skin is the outer protective layer of the body, which is formed from the ectoderm.

4. **Conclusion**: Since all the mentioned structures (retina, eye lens, brain, and skin) are derived from the ectoderm, the correct answer is **B) Ectoderm**.

### Final Answer:
The retina, eye lens, brain, and skin are formed from **B) Ectoderm**.