which of the following is correct w.r.t lymphatic system of human?

Options

A. lymph nodes are site of formation of lymphocytes
B. lymph is devoid of all formed elements which are present in blood
C. both right and left lymphatic duct drain lymph into right subclavian vein
D. lymph transfers material from blood to the body cells and vice versa therefore it acts as a "middle man"

Answer

To determine which statement is correct with respect to the lymphatic system of humans, we will analyze each option provided.

### Step-by-Step Solution:

1. **Analyze Statement A**: "Lymph nodes are sites of formation of lymphocytes."
- Lymphocytes are a type of white blood cell. They are primarily formed in the bone marrow and can mature in the thymus. While lymph nodes serve as sites where lymphocytes can reside and proliferate, they are not the primary site of their formation. Therefore, this statement is **incorrect**.

2. **Analyze Statement B**: "Lymph is devoid of all formed elements which are present in blood."
- Lymph is indeed a tissue fluid that is similar to blood plasma but lacks the formed elements such as red blood cells, white blood cells, and platelets. This statement is **correct**.

3. **Analyze Statement C**: "Both right and left lymphatic duct drain lymph into right subclavian vein."
- The right lymphatic duct drains lymph from the right side of the head, neck, and right upper limb into the right subclavian vein. In contrast, the left lymphatic duct (also known as the thoracic duct) drains lymph from the rest of the body into the left subclavian vein. Thus, this statement is **incorrect**.

4. **Analyze Statement D**: "Lymph transfers material from blood to body cells and vice versa."
- Lymph primarily functions to transport excess tissue fluid back to the bloodstream, thus it moves fluid from the body cells to the blood, not the other way around. Therefore, this statement is also **incorrect**.

### Conclusion:
Based on the analysis, the correct statement regarding the lymphatic system of humans is **Statement B**: "Lymph is devoid of all formed elements which are present in blood."

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