Stain: Orcein and eosin. At the top pseudostratified epithelium (1) followed by a thick layer filled with dark-stained elastic fibers (2). Bundle of smooth muscle fibers (3) (note: there is an artifactual space between the elastic layer and the smooth muscle), belonging to the tunica fibro-musculo-cartilaginea is detached from the underlying hyaline cartilage (4) (note: solitary chondrons in young cat cartilage) and tracheal glands (5)
