The structure of the spleen and its functional implications

Spleens from normal albino rabbits were studied with optical and electron microscopy. There were openings in the walls of the capillaries of the white pulp, in the walls of the large parafollicular sinusoids, and the sinusoids of the red pulp. All types of cells and platelets were seen within the intersinusoidal tissue and also crossing the walls of the sinusoids. The lining of the parafollicular sinusoids was actually formed in part by the cells of the marginal zone. Most of the material that had been phagocytized was in the cells of the intersinusoidal tissue rather than in the cells lining the sinusoids. Erythrocytes and leucocytes in various stages of degeneration comprised the major part of the material that had been phagocytized. The findings are discussed in relation to the route and communications of the circulatory system of the spleen; the sequestration, phagocytosis, and degeneration of erythrocytes; the phagocytosis, distribution, and effect of extracellular materials carried to the spleen by the circulation; the production and interchange of cells between red and white pulp and the general circulation; and the components of the supporting connective tissue of the spleen.