Primary lymphoid organs of the humam body are

Options

A. bone marrow and thymus
B. thymus and lymph nodes
C. bursa of Fabricius and thymus
D. both a and c

Answer

**Step-by-Step Solution:**

1. **Definition of Primary Lymphoid Organs**: Primary lymphoid organs are specialized organs where immature lymphocytes develop and mature into antigen-specific lymphocytes. These organs play a crucial role in the immune system by ensuring that lymphocytes are properly formed and functional.

2. **Identification of Primary Lymphoid Organs**: The two main primary lymphoid organs in the human body are:
- **Bone Marrow**: This is where B lymphocytes (B cells) mature. Bone marrow is a soft tissue found in the hollow interior of bones.
- **Thymus**: This is where T lymphocytes (T cells) mature. The thymus is located in the upper chest, behind the sternum.

3. **Function of Each Organ**:
- **Bone Marrow**: It is responsible for the production and maturation of B cells, which are crucial for the humoral immune response. B cells produce antibodies that help in identifying and neutralizing pathogens.
- **Thymus**: It is essential for the maturation of T cells, which are important for cell-mediated immunity. T cells help in directly killing infected host cells, activating other immune cells, and regulating the immune response.

4. **Conclusion**: Therefore, the primary lymphoid organs of the human body are the **Bone Marrow** and the **Thymus**.

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