Pneumocytes
Pneumocytes

Pneumocytes

The surface epithelial cells of the alveoli, or pneumocytes, are of two types. The type I pneumocytes form part of the barrier across which gas exchange occurs. They can be identified as thin, squamous cells whose most obvious feature is their nuclei. Type II pneumocytes are larger, cuboidal cells and occur more diffusely than type I cells. They appear foamier than type I cells because of they contain phospholipid multilamellar bodies, the precursor to pulmonary surfactant. Capillaries form a plexus around each alveolus. What would happen if the capillaries became leakier? Where would neutrophils that exit the capillaries accumulate?
Answer: Fluid and protein would diffuse across the endothelium and epithelia of the alveoli and accumulate in the air spaces of the lung. Neutrophils that cross the endothelium also transit across the epithelia of the alveoli to accumulate in the air space of the lung.