Monocytes

• Two to eight percent of WBCs are monocytes
• Monocytes are the largest white blood cells
• Monocytes circulate for just a few days before entering peripheral tissues
• Outside the bloodstream, monocytes are called free macrophages and different from immobile fixed macrophages in connective tissues
• Free macrophages are mobile, phagocytic cells
• Macrophages also secrete substances that attract fibroblasts into the region. The fibroblasts then begin producing scar tissue to all of the injured area