This rolling green pasture is a scene common to all of us; it's the landscaping found inside the lungs. The thickets of grass are cilia emerging from the cell membrane. The cilia seen here are in various stages of growth, from the newly sprouted stalks in the top left and bottom right to the more mature cilia on the left side of the image. The landscape is also dotted with clumps of secreted mucus and a ubiquitous field of microvilli. While some of the cell boundaries are easily spotted by fissures, the others can be traced out with careful examination. This particular image is of a ciliated cell culture that has been washed to remove most of its surface mucus. The culture was preserved with formaldehyde and imaged with an environmental scanning electron microscope.
Image credit: Jerome Carpenter and Sheel Shah, University of North Carolina at Chapel Hill