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4. The proliferative phase of wound healing occurs from days 4 to 21 after wounding. During this phase, granulation tissue fills the wound and keratinocytes migrate to restore epithelial continuity. cytokines, and growth factors present in the healing wound, as the list grows daily (7). The exact function for each of these factors is incompletely understood, and the literature is filled with contradictory data. However, it is clear that, unlike the neutrophil, the absence of monocyte/macrophages has severe consequences for healing wounds (8).

For example, neural injury is characterized by little regeneration and much scarring, whereas hepatic and bone injury usually heals primarily through regeneration. It is important to note, however, that the liver can respond to injury with scarring as it does in response to repetitive insults with alcohol during hepatic cirrhosis. Moreover, the same injury in phylogenetically related species can result in very different responses. Thus, limb amputation in newts results in limb regeneration, whereas in humans, only scarring can occur.

This is the process of scar formation. The second process is a recapitulation of the developmental processes that initially created the injured organ. By reactivating developmental pathways the architecture of the original organ is recreated. This is the process of regeneration (5). The dynamic balance between scarring and tissue regeneration is different in different tissues and organs (Fig. 1). For example, neural injury is characterized by little regeneration and much scarring, whereas hepatic and bone injury usually heals primarily through regeneration.