Alkali-induced injury:
Liquefactive necrosis
1-2 days: Thrombosis of small vessels
2-4 days : Newly forming blood vessels , fibroblasts migration
4-7 days: Mucosal sloughing, bacterial invasion, inflammatory response, and development of granulation tissue
> 2 weeks: Collagen deposition
> 3 weeks: Scar retraction => may continue for several months
Acid-induced injury:
Superficial coagulation necrosis
Thromboses the underlying mucosal blood vessels and consolidates the connective tissue => Protective eschar