Question

Select the incorrect statement related to secondary lymphoid organs ?

• A. Splenic white pulp populated mainly by T-lymphocytes
• B. Lymph nodes and spleen are less organized secondary lymphoid tissue
• C. Tonsils protect against antigens entering through nasal and oral epithelial routes
• D. Peyer’s patch is present in the submucosa of the intestine

Answer 1

The correct option is B Lymph nodes and spleen are less organized secondary lymphoid tissue

The lymphoid organs which are mainly composed of lymphocytes occur either as discrete, encapsulated organs or as diffuse tissues.

Secondary lymphoid organs are sites where mature lymphocytes can interact effectively with an antigen and produce effector cells. Examples of secondary lymphoid organs and tissues include spleen, lymph nodes and MALT (Mucosa-associated lymphoid tissue).

Lymph nodes and spleen are highly organised of all the secondary lymphoid organs as are compartmentalized from the rest of the body by a fibrous capsule. Hence option b is incorrect.

Figure : Lymph node

The spleen is compartmentalised into red and white pulp. The red pulp is the site where old and defective erythrocytes are destroyed and removed from the blood while white pulp is the region where blood-borne antigens are trapped and proper immune response takes place. So this region is populated by T-lymphocytes. Hence option a is correct.

Figure : Spleen

Tonsils are nodular structures located at the base of the tongue, at the sides of the back of the mouth, and at the roof of the nasopharynx. It protects the body against the antigens entering through nasal and oral epithelial routes. Hence statement c is correct.

Figure : Tonsils

Peyer’s patch is a secondary lymphoid organ present in the submucosa beneath the lamina propria of the intestine. They possess both T-lymphocytes and B- lymphocytes. Hence option d is correct.

Figure : Peyer’s patch