What changes occur in epithelial tissue during wound healing after injury?

• A. Inflammation occurs but leaves wounds to heal by fibrosis without re-epithelialization.
• B. Inflammation followed by proliferation and migration of basal cells to re-epithelialize the wound, differentiation and remodeling of extracellular matrix; scarring may occur.
• C. Only fibroblasts are involved; epithelial cells do not participate in healing.
• D. Epithelial cells die and are replaced exclusively by scar tissue.

Answer: (B)

The key idea is how epithelial tissue repairs itself after injury. In healing, inflammation sets the stage, but the critical step for restoring the epithelial barrier is re-epithelialization. Basal keratinocytes at the wound edge become activated, migrate across the wound bed as a sheet and then proliferate to rebuild the epithelial layer, re-forming the proper stratified structure and restoring the basement membrane attachment. As this epithelial layer is being reconstituted, the underlying connective tissue remodels its extracellular matrix, with fibroblasts producing and reorganizing collagen and other components to strengthen the tissue. If the injury is deep or extensive, this remodeling can lead to scar formation. This sequence—inflammation, basal cell migration and proliferation to re-epithelialize, followed by ECM remodeling and potential scarring—best captures how epithelial wound healing progresses.