<P> The spleen contains half the body's monocytes in reserve ready to be deployed to injured tissue . Attracted to the wound site by growth factors released by platelets and other cells, monocytes from the bloodstream enter the area through blood vessel walls . Numbers of monocytes in the wound peak one to one and a half days after the injury occurs . Once they are in the wound site, monocytes mature into macrophages . Macrophages also secrete a number of factors such as growth factors and other cytokines, especially during the third and fourth post-wounding days . These factors attract cells involved in the proliferation stage of healing to the area . </P> <P> In wound healing that result in incomplete repair, scar contraction occurs, bringing varying gradations of structural imperfections, deformities and problems with flexibility . Macrophages may restrain the contraction phase . Scientists have reported that removing the macrophages from a salamander resulted in failure of a typical regeneration response (limb regeneration), instead bringing on a repair (scarring) response . </P> <P> As inflammation dies down, fewer inflammatory factors are secreted, existing ones are broken down, and numbers of neutrophils and macrophages are reduced at the wound site . These changes indicate that the inflammatory phase is ending and the proliferative phase is underway . In vitro evidence, obtained using the dermal equivalent model, suggests that the presence of macrophages actually delays wound contraction and thus the disappearance of macrophages from the wound may be essential for subsequent phases to occur . </P> <P> Because inflammation plays roles in fighting infection, clearing debris and inducing the proliferation phase, it is a necessary part of healing . However, inflammation can lead to tissue damage if it lasts too long . Thus the reduction of inflammation is frequently a goal in therapeutic settings . Inflammation lasts as long as there is debris in the wound . Thus, if the individual's immune system is compromised and is unable to clear the debris from the wound and / or if excessive detritus, devitalized tissue, or microbial biofilm is present in the wound, these factors may cause a prolonged inflammatory phase and prevent the wound from properly commencing the proliferation phase of healing . This can lead to a chronic wound . </P>

During the inflammatory phase of the healing process