Lymph vessels are united to form

Options

A. Lymph heart
B. Cisterna chyli
C. Thoracic duct
D. Jugular vein

Answer

To answer the question "Lymph vessels are united to form," we will analyze the options provided and determine the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding Lymph Vessels**: Lymph vessels are part of the lymphatic system, which is responsible for transporting lymph, a fluid that contains white blood cells, proteins, and fats.

2. **Evaluating the Options**:
- **Option A: Lymph Heart**: The lymph heart is an organ that pumps lymph in certain organisms like lungfish, amphibians, and some reptiles. However, it is not a structure formed by the union of lymph vessels. Therefore, this option is incorrect.

- **Option B: Chyle**: Chyle is a milky bodily fluid consisting of lymph and emulsified fats, which is present in the intestinal trunk of the thoracic duct. Chyle is not a structure formed by lymph vessels; it is a component of lymph. Thus, this option is also incorrect.

- **Option C: Jugular Vein**: The jugular vein is a major vein in the neck that carries blood back to the heart. While it may contain lymphatic vessels, it is not formed by the union of lymph vessels. Hence, this option is incorrect as well.

- **Option D: Thoracic Duct**: The thoracic duct is the largest lymphatic vessel in the body. It collects lymph from various parts of the body, including the intestinal trunk and lumbar trunks, and transports it back to the bloodstream. This is the structure formed by the union of lymph vessels.

3. **Conclusion**: After evaluating all the options, the correct answer to the question "Lymph vessels are united to form" is the **thoracic duct**.

### Final Answer:
**Lymph vessels are united to form the thoracic duct.**

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