Internal structure of the spleen showing vascular supply and follicle organization
Internal structure of the spleen showing vascular supply and follicle organization
The afferent splenic artery (red) enters the spleen and branches into central arterioles, which end in cords in the red pulp. Slits between endothelial cells in the cords allow blood to pass into the venous sinuses, which coalesce into collecting veins that lead to the splenic vein (blue). (A) Cross-sectional view. The central arterioles are surrounded by lymphocyte-rich white pulp. The periarteriolar lymphoid sheaths contain mostly T cells, and the follicles contain mostly B cells. The marginal zone contains macrophages that bind polysaccharide antigens. Venous blood enters red pulp, which is rich in macrophages. The red pulp is where aging and poorly deformable RBCs undergo phagocytosis. (B) Relationships between the central arteriole and zones in the white pulp. The white pulp is the primary site for opsonizing encapsulated organisms.