Light micrograph of foamy histiocytes. Histiocytes are a type of inflammatory cell found in tissues. When histiocytes react to something, they can take on a ?œfoamy??appearance. The ?œfoam??is made up of numerous vacuoles in the cells??cytoplasm (many small white bubbles). The cytoplasm of each cell contains a single nucleus (dark blue dots). Intermixed with the foamy histiocytes in this image are red blood cells (bright red). Haematoxylin and eosin stained tissue section. Magnification: 400x when printed at 10cm.