MICROANATOMY

Detailed explanation-1: -Secondary lymphoid organs: These organs include the lymph nodes, the spleen, the tonsils and certain tissue in various mucous membrane layers in the body (for instance in the bowel). It is in these organs where the cells of the immune system do their actual job of fighting off germs and foreign substances.

Detailed explanation-2: -Because of their roles in the production of B and T cells, the thymus and bone marrow are considered primary lymphoid organs. Secondary lymphoid organs include lymph nodes and spleen, which filter lymph and blood, respectively, and where naïve B and T cells are introduced to antigens.

Detailed explanation-3: -The fluid contained within lymphatic vessels is called lymph (lympha means “clear water"), a watery fluid that contains lymphocytes and other types of white blood cells, as well as proteins and lipids.