Scheme of secondary lymphatic nodule in spleen (human)

A. histological impression of a follicle or nodule B. outline of impression 1. pulpa artery; 2. central artery ; 3. lymphatic sheath; 4. lymphatic nodule; 5. thymus-dependent area (periarteriolar lymphatic sheath or PALS), composed of Th subset lymphocytes; 6. mantle zone with mainly nave B lymphocytes; 7. lighter stained germinal centre with B-memory lymphocytes, reticular cells and macrophages; 8. dendritic antigen-presenting cells (APC, border cells, metallophilic cells); 9. anastomosing capillaries within a reticulin scaffold surrounded by dendritic APC; 10. marginal sinus zone (perilymphoid zone) between the red and white pulps; this zone immediately surrounds the nodule and is composed of a reticulin scaffold with APC; the zone comprises concentrically arranged anastomosing fine vascular channels that receive the blood from radial arterioles from the central artery or arteriole Background: About 10% of the blood is drained either into the sinusoid or directly into venous sinuses located on the outer portion of the marginal zone. In this perilymphoid zone the marginal zone sinuses are arranged in three concentric systems: marginal zone network followed by marginal sinuses and perimarginal cavernous sinuses enclosing the APC. This zone is thought to be involved in phagocytosis and or antigen-presenting to initiate an immune reaction.; 11. red pulp with sinusoids; 12. rectangle is displayed in the scheme of electron microscopy (see POJA -L976B)