The present epithelium is composed of ciliated columnar cells (Ci) and mucous goblet cells (+). The mucous goblet cells show a dark triangular nucleus at their base and a large pocket containing mucigen granules stained green. Many small basal cells (B) are present along the basement membrane between the basal extremities of ciliated and goblet cells.

A thick layer of type I collagen (*), stained green, separates the epithelium from the underlying connective tissue of the lamina propria (LP).

Stain: Masson’s Trichrome
Magnification: ×500