Which of the following gland is located on the dorsal side of the heart and aorta?

Options

A. Adrenal gland
B. Parathyroid gland
C. Thyroid gland
D. Thymus

Answer

To solve the question "Which of the following gland is located on the dorsal side of the heart and aorta?", we will analyze each option provided.

### Step-by-Step Solution:

1. **Understand the Question**: We need to identify which gland is located on the dorsal side of the heart and the aorta.

2. **Evaluate the Options**:
- **Option 1: Adrenal Glands**:
- The adrenal glands are situated above each kidney. They are not located near the heart or aorta, hence this option is incorrect.

- **Option 2: Parathyroid Glands**:
- The parathyroid glands are located at the back of the thyroid gland in the neck. They are not positioned on the dorsal side of the heart or aorta, making this option incorrect as well.

- **Option 3: Thyroid Gland**:
- The thyroid gland is located in the neck, which is not near the heart or aorta. Therefore, this option is also incorrect.

- **Option 4: Thymus Gland**:
- The thymus gland is a lobular structure located in the thoracic cavity, specifically on the dorsal side of the heart and aorta. It plays a crucial role in the immune system, particularly in the maturation of T-lymphocytes.

3. **Conclusion**: Based on the analysis, the gland that is located on the dorsal side of the heart and aorta is the **Thymus Gland**. Therefore, the correct answer is **Option 4: Thymus**.