find the odd one w.r.t germ layers which form the following structures?

Options

A. Gonads
B. Adrenal cortex
C. kidneys
D. Iris muscle

Answer

To solve the question of which structure is the odd one out with respect to germ layers, we need to identify the germ layer from which each of the given structures is derived. The three primary germ layers are ectoderm, mesoderm, and endoderm.

### Step-by-Step Solution:

1. **Identify the Germ Layers**:
- Ectoderm: This layer forms structures such as the skin and nervous system.
- Mesoderm: This layer forms muscles, bones, and various organs including the gonads.
- Endoderm: This layer forms the inner linings of the digestive tract and other internal organs.

2. **Analyze Each Structure**:
- **Gonads**: These are reproductive organs and are derived from the mesoderm.
- **Adrenal Cortex**: This is part of the adrenal glands and is also derived from the mesoderm.
- **Kidney**: The kidneys are excretory organs and are formed from the mesoderm.
- **Iris Muscle**: This muscle is part of the eye and is derived from the ectoderm.

3. **Compare the Structures**:
- Gonads, adrenal cortex, and kidneys are all derived from the mesoderm.
- The iris muscle, however, is derived from the ectoderm.

4. **Identify the Odd One Out**:
- Since the iris muscle is the only structure derived from the ectoderm while the others are derived from the mesoderm, it is the odd one out.

5. **Conclusion**:
- The answer to the question is the **iris muscle**, as it is the only structure formed from the ectoderm, while the others are formed from the mesoderm.