Outer Cortex

• The outer cortex of lymph nodes consists EGG-SHAPED aggregates of B CELLS called LYMPHATIC NODULES (follicles).
• Primary lymphatic nodule: consisting chiefly of B CELLS
• Secondary lymphatic nodule: form in response to an ANTIGEN (a foreign substance) and are sites of PLASMA CELLS and memory B CELL formation.
• The center of a secondary lymphatic nodule contains a region of LIGHT-STAINING cells called a GERMINAL CENTER.
• The germinal center consists of germinal center are B cells, follicular dendritic cells (antigen presenting cell), and macrophages.