Constitute of 50% of lymphoid tissue which located within the major respiratory, digestive & urogenital tract is known as :-

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks for a specific type of lymphoid tissue that constitutes 50% of the lymphoid tissue in the human body and is located within the major respiratory, digestive, and urogenital tracts.

2. **Identifying the Tissue:** The tissue in question is known as MALT, which stands for Mucosa-Associated Lymphoid Tissue.

3. **Components of MALT:** MALT consists of various immune cells, including:
- T-lymphocytes (T-cells)
- B-lymphocytes (B-cells)
- Macrophages

4. **Location of MALT:** MALT is distributed in association with mucosal tissues throughout the body, particularly in areas such as:
- The respiratory tract
- The digestive tract
- The urogenital tract

5. **Significance of MALT:** MALT plays a crucial role in the immune response, as it helps protect the body from pathogens that enter through mucosal surfaces.

6. **Final Answer:** Therefore, the answer to the question is Mucosa-Associated Lymphoid Tissue (MALT).

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