At least two, sometimes three rows of nuclei are seen in the pseudostratified columnar epithelium lining the trachea. The nuclei belong to cells which are all in contact with the basement membrane. The epithelial lining of the trachea is also one of the few examples of a basement membrane clearly visible in H&E stained sections. Epithelial cells can be ciliated or they can be goblet cells (unicellular exocrine glands). Basal cell regenerate other cell types of the epithelium. Capillaries and small vessels are visible in the connective tissue beneath the epithelium.
