F. Spleen

1. LOCATION: An unpaired, soft abdominal organ situated on the left between the stomach, L. kidney and the diaphragm. Adapted to filter and store blood.

2. ORGANIZATION: Highly organized ovoid organ: Capsule of D.I.FECT with visceral peritoneum (mesothelium); Trabeculae -- D.I.-FECT; White Pulp of lymphocytes; Red pulp -- of pulp cords and splenic sinuses. Complex vascular system; Lymphatic vessels in white pulp; Vasomotor and sensory nerve fibers.

3. STROMA: Reticular C.T. of reticular cells and fibers (mesodermal origin); associated with macrophages. The reticulum supports both white pulp and red pulp. The reticular fibers are continuous with the fibers of trabeculae and the supporting reticular lamina of the walls of sinuses.

4. PARENCHYMA: Lymphocytes form the elongate, branched strands of white pulp, which contain nodules with germinal centers; Erythrocytes, lymphocytes, plasma cells, monocytes, macrophages and sometimes megakaryocytes are present in the red pulp.

5. DIAGNOSTIC FEATURES: Red pulp and arrangement of white pulp (See Figure 2):
The spleen section shows the internal organization of the spleen. (CLICK on the spleen section or the right GC in the spleen section above for actual images then CLICK the BACK button to return.) The splenic sinuses are lined by elongated endothelial cells. This sinus wall is illustrated above. On the right the diagram depicts the relationship between the splenic vasculature and the white pulp and sinusoids. Abbreviations: GC, germinal center; PALS, periarteriolar lymphoid sheath.
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