Inflammatory response. Light micrograph of a section through a venule (small vein), showing the vascular phase of the inflammatory response. This is characterised by slower blood flow with and accumulation of blood cells - notably the preferential attraction of white blood cells (leucocytes) along the inner vessel wall. This process is referred to as margination. The leucocytes are chiefly neutrophils (polymorphonuclear leucocytes) arriving at a site of tissue damage where, in response to specific chemo attractive signals, they become adherent to the endothelium of the vessel wall. Magnification: x400, when printed 10 centimetres high.