Spleen with central artery in lymphatic nodule (human)

Stain: A: Silver stain (Gomori). B: Trichrome (Goldner). In A: the reticular fibers (2) around the PALS (periarteriolar lymphatic sheath) and continuing in and around the marginal zone are stained black, illustrating the reticular framework of the lymphatic nodule. (1) central arteries. (4) red pulp sinusoids. In B: the lymphatic nodule or follicle contains a central artery (1) surrounded by the lymphatic sheath (PALS composed of concentric layered Th subset lymphocytes). The nuclei of dendritic cells (3) or antigen-presenting cells (APC's) are stained pale and contain a conspicuous nucleolus.