General pathology · Tissue repair
Tissue repair: regeneration or scar; labile, stable and permanent cells !
- Topic
Damaged tissue heals either by growing back the same cells or by filling the gap with a scar; which one depends on the cells and the framework.
Updated 2026-11-01
What it is
Repair restores tissue after injury in two ways. Regeneration replaces lost cells with cells of the same type and restores normal structure; it needs cells that can divide and an intact extracellular matrix framework. Scar formation fills the defect with collagen; it restores continuity but not function. Most repairs combine both, and the balance depends on the type of cells, how severe the injury is and whether the framework survived.
Key facts
- Regeneration needs intact extracellular matrix: the basement membrane gives cells a template to rebuild the original architecture.
- If the framework is destroyed (abscess, infarct, severe necrosis), even regenerating organs heal with scar: cirrhosis has nodules separated by fibrous bands.
- Growth factors drive repair: EGF and TGF-α (epithelia), HGF (hepatocytes), VEGF (vessels), PDGF and FGF (fibroblasts), TGF-β (collagen, fibrosis).
- In the brain, dead tissue is cleared by macrophages (liquefactive necrosis) and the gap is lined by astrocytes (gliosis), not collagen.
Proliferative capacity of tissues
| Group | Behaviour | Examples |
|---|---|---|
| Labile (continuously dividing) | Lost cells are constantly replaced from stem cells | Epidermis; epithelium of the gut, mouth, cervix and ducts; bone marrow |
| Stable (quiescent) | Rest in G0 but can divide after injury or loss of mass | Hepatocytes, renal tubular cells, pancreas, fibroblasts, endothelium, smooth muscle |
| Permanent (non-dividing) | Do not divide meaningfully; injury heals by scar (heart) or glial scar (brain) | Neurons, cardiomyocytes; skeletal muscle has limited repair through satellite cells |
Clinical notes
- A myocardial infarction always ends in a collagen scar because cardiomyocytes are permanent cells.
- Acute tubular injury in the kidney can recover fully because tubular cells regenerate on an intact basement membrane.
- Bone, mucosae and liver can regenerate almost completely when the framework is preserved.
Test yourself
Think of the answer, then tap the question to see it.
Why does a myocardial infarct heal with a scar?
Cardiomyocytes are permanent cells that cannot divide meaningfully, so dead muscle is replaced by granulation tissue and then collagen.
Hepatocytes are stable cells, yet cirrhosis is full of scar. Why?
Repeated injury destroys the reticulin framework and drives fibrosis, so regeneration forms disorganised nodules surrounded by fibrous septa.
Which tissues are made of labile cells?
Epidermis, gastrointestinal epithelium, bone marrow, epithelium of the cervix and urinary tract.
Related
- Granulation tissue and scar formation
- Liver regeneration
- Fibrosis in organs: TGF-β and the myofibroblast
- Healing of skin wounds: first and second intention
- Outcomes of acute inflammation: resolution, abscess, scar or chronic inflammation
- Hyperplasia: physiologic and pathologic
Related conditions
- Myocardial Infarction (Heart Attack)
- Cirrhosis
- Ischaemic stroke
- Acute kidney injury
- Viral hepatitis
- Burns (thermal, chemical, electrical; inhalation injury)
- Chagas cardiomyopathy
Elsewhere in DurgiPedia
- Stem cells and tissue renewal: labile, stable and permanent tissues
- Cell cycle, mitosis and meiosis
- Extracellular matrix: collagen types, elastin, ground substance
- Wound healing: phases and scar
- Liver: lobule, acinus, hepatocytes, sinusoids, Kupffer cells
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: 4.6 Tissue Injury and Aging (OpenStax (Anatomy and Physiology 2e), 2022); 23.6 Accessory Organs in Digestion: The Liver, Pancreas, and Gallbladder (OpenStax (Rice University), 2022); Cirrhosis: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.