Electron-microscopic observations of the alveolar brush cell of the rat.

The alveolar brush cells in the rat lung were observed by transmission electron microscopy. The general structural features of the brush cells in this report were basically in agreement with earlier descriptions. However, this report is the first to detect long, thick microvilli with a unique form protruding into the alveolar lumen in parallel with the basement membrane, not vertically to the basement membrane. Moreover, intranuclear inclusions in the nucleus were observed for the first time in the alveolar brush cells in this study.