Tissue: The Living Fabric
Te repair process that we have just described follows heal-
ing of a wound (cut, scrape, puncture) that breaches an epithe-
lial barrier. In simple
(a pimple or sore throat), healing
is solely by regeneration. Only severe (destructive) infections
lead to clot formation or scarring.
epithelium thickens until it ﬁnally resembles the adjacent
skin. Te end result is a fully regenerated epithelium, and an
underlying area of scar tissue. Te scar may be invisible, or
visible as a thin white line, depending on the severity of the
Regeneration and ﬁbrosis effect
• The fbrosed area matures and
contracts; the epithelium thickens.
• A Fully regenerated epithelium with
an underlying area oF scar tissue results.
Inﬂammation sets the stage:
• Severed blood vessels bleed.
• In±ammatory chemicals are released.
• Local blood vessels become more permeable,
allowing white blood cells, ±uid, clotting
proteins, and other plasma proteins to seep
into the injured area.
• Clotting occurs; surFace dries and Forms a scab.
Blood clot in
Organization restores the blood supply:
• The clot is replaced by granulation
tissue, which restores the vascular
• ²ibroblasts produce collagen fbers that
bridge the gap.
• Macrophages phagocytize dead and
dying cells and other debris.
• SurFace epithelial cells multiply and
migrate over the granulation tissue.
Tissue repair of a nonextensive skin wound: regeneration and ﬁbrosis.