Page 78 - Concise Pathology for Exam Preparation ( PDFDrive )

3 Healing and Repair 63

Wound

• Filled with blood clot and inflammatory cells Day 1
• Neutrophils appear at the margin of the wound

• Neutrophils largely replaced by macrophages
• Granulation tissue formation begins and infiltrates the incision space
• Collagen fibres form at the margins of the incision and are laid down vertically
• Thickening of the epithelial layer due to epithelial cell proliferation and Day 3
migration of epithelial cells along incised margins

• Incisional space is filled with granulation tissue
• Neovascularization is at its peak
• Collagen fibres become abundant and bridge the incisional gap Day 5
• Epidermis regains its normal thickness
• Differentiation of surface cells yields mature epidermal architecture

• Continued accumulation of collagen and proliferation of fibroblasts Day 7
• Regression of vessels and blanching

• Scar tissue formation by the end of the first month
• Gradual gain in tensile strength overtime
FLOWCHART 3.5. Steps in healing by primary intention.

24 hours
Scab

Epitheilum Fibrin clot
Large gaping wound
Clean
incised Neutrophils
wound

3 to 7 days

Epithelial
regeneration
Granulation tissue
Macrophages
Fibroblasts
New capillaries

Weeks

Regenerated
epithelium

Collagen Wound
contraction
Fibroblasts
Fibrous union
A B

FIGURE 3.4 A and B. Healing by (A) primary and (B) secondary intentions.
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