FIGURE 7-2 Illustration of the various types of cellular arrangements of epithelium that line internal body passages, including the respiratory system. Specialized cells, such as goblet cells, that secrete mucus into the passages are often interspersed with the epithelial cells. Clara cells take the place of goblet cells in certain parts of the respiratory system. A: simple squamous; B: simple cuboidal; C: simple columnar; D: ciliated columnar; E: pseudostratified ciliated columnar with goblet cells; and F: stratified squamous. SOURCE: Adapted from Stedman's Medical Dictionary, 1976, with permission from Williams & Wilkins.