Confocal light micrograph of macrophage cells (purple) patrolling tissue. A fluorescent marker has been used to highlight actin filaments (white). Actin filaments make up part of the cytoskeleton, which maintains the cells shape, allows some cellular mobility and is involved in intracellular transport. The circular actin structures are podosomes, structures that form on the outer membrane of cells in the early stages of cell adhesion. Macrophages are cells of the bodys immune system. They phagocytose (engulf) and destroy pathogens, dead cells and cellular debris. Magnification: x630 when printed at 10cm.