Phagocytosis in small splenic blood vessel (mouse)

Electron microscopy. Stain: Peroxidase reaction with diaminobenzidin staining. A diversity of red blood cells is black-stained due to the staining of hemoglobin by oxidized benzidin. Circulating lymphocytes (2) in the lumen (*) remain unstained. An oblong monocyte (1) developing into a macrophage has already ingested two black-stained erythrocytes. The cell also contains stippled large lysosomal vacuoles. Note that the developing macrophage (1) contains dark-stained small granules but still shows negative reacting profiles of endoplasmic reticulum (arrows). The free side of the phagocyte shows finger-like podia into the lumen. The underlying endothelial lining as well as few smooth muscle cells are negative.