Endothelial vacuoles. Coloured atomic force micrograph (AFM) showing vacuoles (pits) in endothelial cells. Vacuoles are membrane-bound compartments within a cell that are used to remove waste products from the endothelial cell. Endothelial cells are flat and line all of the body's, blood vessels. An atomic force microscope is used to study surfaces at an atomic level. An extremely fine spring-mounted probe is moved across the surface at a constant height. Any deflections are recorded and converted into a computer map of the surface. Magnification: x10,000 when printed at 10 centimetres wide.