Which part of the lymph node contains the germinal centers where B cells proliferate?

• A. The outer cortex
• B. The inner cortex
• C. The medulla
• D. The capsule

Answer: (A)

The outer cortex of the lymph node is the area that contains germinal centers, which are critical for the proliferation and maturation of B cells. When B cells encounter their specific antigen, they migrate to these germinal centers within the outer cortex, where they undergo rapid division and differentiation. This process is essential for the immune response, as it leads to the production of plasma cells that secrete antibodies.

The structure of the lymph node supports this function; the outer cortex is rich in follicles where B cells are organized. Within these follicles, the germinal centers form in response to antigen stimulation, allowing for affinity maturation and the generation of memory B cells, which are crucial for long-term immunity.

In contrast, the inner cortex, medulla, and capsule do not serve this specific function. The inner cortex primarily contains T cells and does not have germinal centers. The medulla includes medullary cords and sinuses where more mature immune cells reside but lacks the proliferation niches for B cells. Lastly, the capsule is simply the protective outer covering of the lymph node and has no direct role in B cell proliferation.