Germinal center
Germinal centers or germinal centres (GC) are sites within secondary lymphoid organs where mature B lymphocytes proliferate, differentiate, and mutate their antibody genes (through somatic hypermutation), and switch the class of their antibodies (for example from IgM to IgG) during a normal immune response to an infection. They develop dynamically after the activation of follicular (Fo) B cells by T-dependent antigen.