Lymph nodes are the most structurally complete peripheral immune organs and are widely distributed throughout the body in non-mucosal areas where lymphatic channels converge. Their organization includes superficial cortical area, paracortical area and medulla, and the germinal center is located in their superficial cortical area. Lymph nodes increase in size, and the formation of the germinal center is an important symbol of the humoral immune response, and the lymph nodes gradually disappear after the antigen is removed. The process of germinal center formation: after recognizing antigen and interacting with Th cells, the initial B cells migrate to the primary lymph nodes and divide and proliferate to become large and naive germinal center mother cells, which constitute the dark zone of the germinal center. These cells continue to proliferate and differentiate, generating smaller germinal center cells that constitute the bright zone. The constantly dividing and proliferating B cells are pushed to the outer side, forming a small nodule cap. The formation of the lymph node germinal center is the proliferation and differentiation of the initial B cells in the superficial cortical area of the lymph node after antigenic stimulation, forming a site of continuous lymphocyte production.