24 August 2012
Vol 337, Issue 6097

About The Cover

Cover image expansion

COVER Artist's rendering of the airway epithelial cell surface in human lungs. The airway surface is lined by arrays of cylindrical cilia (shown as yellow projections) that are 7 micrometers long and 200 nanometers in diameter. The cilia and airway surface are covered by tethered biomacromolecules (shown as green hairs) that form dense, brushlike structures. These epithelial brushes protect the airways from infectious agents and ensure efficient flow of mucus from healthy lungs. See page 937. For the story behind the cover, go to Image: Yan Liang (, Li-Heng Cai, Michael Rubinstein