Germinal center

These are the central portion of the secondary follicles in lymphoid tissue (e.g. lymph node, MALT, or Spleen). As the primary follicle (no germinal center) gets antigen stimulated, the primary follicle then turns into a secondary follicle (germinal center is in the middle of these secondary follicles). Upon antigen stimulation, B-cells within these germinal centers continue their maturation cycle by undergoing somatic hypermuatation and heavy chain class switching which could ultimately lead to the development of a plasma cell or memory B-cell.