Alveolar Type I Epithelial Cells: The Forgotten Cells in Fetal Lung Development and Lung Injury

Abstract

The alveolar surface of the lung is covered by large flat type I epithelial cells. Even though type I cells represent only around 10% of the cells present in the alveolus; they cover much of the surface area in the developed lung. Given their thinness and proximity to the capil-lary endothelium; it is well accepted that type I cells play an important role in gas exchange.