Mark odd one w.r.t. origin from germinal layers.

Options

A. Sclera of eye
B. Adrenal cortex
C. Pituitary gland
D. Notochord

Answer

To determine the odd one out with respect to origin from germinal layers, we need to analyze the origins of each option provided. The three primary germ layers are ectoderm, mesoderm, and endoderm, and each gives rise to different structures in the body.

1. **Identify the options**: The options provided are:
- Sclera of the eye
- Adrenal cortex
- Pituitary gland
- Notochord

2. **Determine the origin of each structure**:
- **Sclera of the eye**: The sclera is the white outer coat of the eyeball and originates from the **ectoderm**.
- **Adrenal cortex**: The adrenal cortex is part of the adrenal glands and originates from the **mesoderm**.
- **Pituitary gland**: The pituitary gland has a dual origin; the anterior lobe originates from the **ectoderm** (Rathke's pouch), while the posterior lobe originates from the **neuroectoderm**.
- **Notochord**: The notochord is a rod-like structure that forms the primitive axis of the embryo and originates from the **mesoderm**.

3. **Compare the origins**:
- Sclera: Ectoderm
- Adrenal cortex: Mesoderm
- Pituitary gland: Ectoderm (anterior) and neuroectoderm (posterior)
- Notochord: Mesoderm

4. **Identify the odd one out**:
- The adrenal cortex and notochord both originate from the mesoderm.
- The sclera and pituitary gland (specifically its anterior lobe) originate from the ectoderm.
- However, the pituitary gland is unique because it has a dual origin (ectoderm and neuroectoderm), while the other structures have a more straightforward origin.

5. **Conclusion**: The odd one out is the **pituitary gland** due to its unique dual origin compared to the other options.