Granulation Tissue

After tissue damage, repair process starts. It can begin as early as 24 hours. Fibroblasts and endothelial cells begin proliferating to form a specialized type of tissue that is the hallmark of healing called granulation tissue.

The term derives from its pink, soft, granular appearance on surface of wound but its histological features are:

1. Formation of new blood vessels called angiogenesis
2. Proliferation of fibroblasts

These new vessels are leaky, allowing the passage of proteins and red cells into extravascular spaces. Thus the new granulation tissue of often edematous.

Angiogenesis

In this process, pre-existing blood vessels send out capillary buds to form new vessels. The processes involved in it are:

1. Proteolytic degradation of extracellular matrix
2. Migration and chemotaxis of extracellular matrix
3. Proliferation of endothelial cells
4. Lumen formation
5. Maturation

The process of angiogenesis is mediated by growth factors (VEGF, TGF-beta)

Migration and proliferation of fibroblasts

It is triggered by FGF, PDGF

Deposition of extracellular matrix

It is done by deposition of proteins and collagen.

Maturation and organization of fibrous tissue

Factors affecting wound healing

Systemic Factors

1. Vitamin C
2. Collagen synthesis
3. Diabetes mellitus
4. Inadequate blood supply
5. Administration of glucocorticoids

Local Factors

1. Infections
2. Early mobilization of wound
3. Foreign body fragments

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