Read the following statements carefully: (A) Primary lymphoid organs provide the sites for interaction of lymphocytes with the antigen. (B) Thymus is quite large at the time of birth but keeps reducing in size with age. (C) Peyer's patches of small intestine and appendix are secondary lymphoid organs. (D) MALT constitutes about 20 percent of the lymphoid tissue in the human body. How many of the above statements are

Step-by-step solution

Statement (A) is incorrect because secondary lymphoid organs (not primary) provide the sites for interaction of lymphocytes with the antigen. Primary lymphoid organs (bone marrow and thymus) are where immature lymphocytes differentiate into antigen-sensitive lymphocytes. Statement (B) is correct. The thymus is quite large at the time of birth but keeps reducing in size with age, and by the time puberty is attained it reduces to a very small size. Statement (C) is correct. Spleen, lymph nodes, tonsils, Peyer's patch