Type I Cells

Alveolar epithelial type I (AT1) cells are large, squamous cells with elongated thin cytoplasmic processes covering the majority of the gas exchange surface of the lung that play an active role in alveolar homeostasis. AT1 cells are derived mainly from AT2 cells during development and following injury, but also arise from other progenitors. AT1 cells constitute a heterogeneous population and while initially considered to be terminally differentiated, in certain circumstances, they can both self-renew and differentiate into AT2 cells. Next generation sequencing and lineage tracing studies have set the stage for more in-depth characterization of AT1 cell function and biology.