Secondary lymphoid organs, such as the lymph nodes, spleen, and mucosa-associated lymphoid tissues, each have distinct features that are important for their role in initiating immune responses focused on different anatomical compartments (i.e., the peripheral tissues, the blood, or the gastrointestinal tract, respectively). Yet these organs share some overall structural features, such as distinct T-cell and B-cell zones. One major difference between these organs is:
A) The presence versus the absence of macrophages and dendritic cells
B) Their function in bringing rare naive lymphocytes into contact with their specific antigen
C) The ability of lymphocytes to enter the organ from the blood
D) The mechanism by which antigens or pathogens enter the organ
E) The ability of naïve T cells to be activated and proliferate in the organ

Question

Quizplus · Accepted Answer

The mechanism by which antigens or pathogens enter the organ is a major difference among secondary lymphoid organs. For example, antigens enter lymph nodes through lymphatic vessels, the spleen filters antigens from the blood, and mucosa-associated lymphoid tissues directly sample antigens from the mucosal surfaces.

Secondary Lymphoid Organs, Such as the Lymph Nodes, Spleen, and Mucosa-Associated