The lumen of the trachea (above) is lined with a pseudostratified columnar epithelium (E) composed of intensely stained ciliated cells and lightly stained goblet mucous cells (+).

Underlying this epithelium, the lamina propria composed of loose connective tissue, contains the profile of a sero-mucous gland (G).

Deeper in the wall of the trachea, a layer of dense connective tissue stained green (*) is next to the plate of hyaline cartilage (C).

Stain: Masson’s Trichrome
Magnification: ×150