Question

Lymphoid tissue is found in
A. Thymus
B. Tonsils
C. Lymph nodes
D. All of the above

Answer 1

Hint: Organized structures that support the immune system are known as lymphoid tissues. The primary lymphoid tissues are the site of lymphocyte production and development and are commonly found in primary and secondary lymph organs.

Complete answer: The lymphoid tissues are highly organized tissues present in lymphoid organs: thymus and lymph nodes. Primary lymphoid organs include bone marrow and thymus, whereas secondary lymphoid organs include tonsils, lymph nodes, spleen, Peyer’s patches, and mucosa-associated lymphoid tissue (MALT). They are the tissues that make up the lymphatic system. Different types of cells are found in the lymphatic system such as reticular cells, lymphocytes, etc. These cells help in transporting lymph, which is a fluid that helps in fighting infections throughout the body. They also act as the site for the production and development of lymphocytes. In the bone marrow, the lymphoid tissue is mixed with red blood cells or erythrocytes. The most diffused form of lymphoid tissue is found beneath the epithelial membranes in the loose connective tissue spaces such as those that line the gastrointestinal tract and respiratory system.
Therefore, the correct answer is option D.

Note: Lymphoid tissues can be primary or secondary that depends upon the stage of the lymphocyte development and maturation. They develop after the fifth week of gestation from the venous endothelial tissues. They also help in initiating the adaptive immune response.