Scanning electron microscope surface morphometry of type II alveolar lung cell response to urethane in strain A mice

Quantitative scanning electron microscope (SEM) examination of the time course of type II cell hyperplasia in mice exposed to a single i.p. injection of urethane is presented. Counts of type II cells from random alveoli suggest that, compared to controls, a significant depression in type II cell numbers occurs during the first week, followed by a doubling in the next 3 to 4 week period. This supports conclusions of earlier studies done with thin sections and light morphometric techniques. The use of a SEM as the morphometric tool is statistically more efficient, however, since initial sample preparation is easier, samples are larger in area, resolution is higher and, most importantly, the amount of surface area available for examination is many times greater than that presented by light microscope examination of cross sections with equivalent magnification.