LM of pseudostratified ciliated columnar (respiratory) epithelium with goblet cells. The airway lumen (*) is indicated. Two or three layers of nuclei are visible. Tall columnar cells (CC) with elongated nuclei and apical cilia intermingle with pale-stained goblet cells (GC) whose washed-out appearance is due to mucus. One row of small basal cells (BC) rests on a basement membrane (arrows). The connective tissue at bottom is the lamina propria. 565×. H&E.

EM of one cilium in longitudinal section. This surface specialization is a feature of cells in respiratory epithelium. It consists of a typical 9 + 2 arrangement of microtubule doublets, which make up the axoneme. A basal body (BB), at the base, has nine microtubule triplets, normally in a 9 + 0 configuration. 20,000×. (Courtesy of Dr. W. A. Webber)