Iris muscles of eye are formed from

Options

A. mesoderm
B. endoderm
C. ectoderm
D. both (1) and (2)

Answer

### Step-by-Step Solution:

1. **Identify the Question**: The question asks about the origin of the iris muscles of the eye, specifically which germ layer (mesoderm, endoderm, ectoderm, or a combination) they are formed from.

2. **Understand the Germ Layers**:
- **Mesoderm**: This germ layer is responsible for forming connective tissues, bones, cartilage, and muscles (both striated and smooth).
- **Endoderm**: This layer primarily forms the epithelial linings of the gastrointestinal and respiratory tracts.
- **Ectoderm**: This layer gives rise to the sensory epithelia of the eye and other structures.

3. **Evaluate Each Option**:
- **Mesoderm**: While it forms muscles, it does not specifically form the iris muscles.
- **Endoderm**: This layer is not involved in muscle formation related to the eye, as it focuses on epithelial linings.
- **Ectoderm**: This layer is responsible for the formation of sensory structures in the eye, including the iris muscles.

4. **Eliminate Incorrect Options**:
- Since mesoderm and endoderm do not contribute to the iris muscles, they can be eliminated.
- The option stating both mesoderm and endoderm can also be eliminated.

5. **Select the Correct Answer**: The only remaining option is ectoderm, which is indeed the correct answer as it forms the iris muscles of the eye.

### Final Answer:
The iris muscles of the eye are formed from the **ectoderm**.

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