FIGURE 1.

Schematic view of stromal elements in the spleen. T and B cells enter the spleen white pulp area via from the marginal zone via bridging channels (BC). Cells first enter the T cell zone of the white pulp, the PALS (peri-arteriolar sheath) in which fibroblast reticular cells (FRC) are the predominant stromal element. In the B cell zones, the follicles, stromal cells form a less dense network and here the follicular dendritic cells (FDCs) play an important role in B cell activation. PALS and follicles are surrounded by the marginal zone (MZ). At the border of marginal zone and T and B cell zone, the marginal reticular cells (MRC) can be found. The bridging channels also form the route of exit for lymphocytes from the white pulp. B cells that have undergone differentiation and maturation in the follicles may exit the white pulp to localize as plasma cells (PC) in the red pulp (RP).