Which cell type proliferates to restore the alveolar epithelium after injury?

Which cell type proliferates to restore the alveolar epithelium after injury?

• A. Type I pneumocytes
• B. Type II pneumocytes
• C. Alveolar macrophages
• D. Goblet cells

Answer: (B)

Alveolar repair after injury is driven by alveolar type II pneumocytes. These cuboidal cells act as progenitors for the alveolar epithelium, proliferating to replace damaged cells and then differentiating into the flat type I cells that form the gas-exchange surface. Type I pneumocytes are thin and specialized for diffusion but have limited capacity to divide, so they’re not the source of regeneration. Alveolar macrophages reside in the airspaces to clear debris, and goblet cells are in the conducting airways producing mucus, not involved in alveolar repair. Hence, the proliferating cells restoring the alveolar lining are type II pneumocytes.

Alveolar repair after injury is driven by alveolar type II pneumocytes. These cuboidal cells act as progenitors for the alveolar epithelium, proliferating to replace damaged cells and then differentiating into the flat type I cells that form the gas-exchange surface. Type I pneumocytes are thin and specialized for diffusion but have limited capacity to divide, so they’re not the source of regeneration. Alveolar macrophages reside in the airspaces to clear debris, and goblet cells are in the conducting airways producing mucus, not involved in alveolar repair. Hence, the proliferating cells restoring the alveolar lining are type II pneumocytes.