Figure 3b (below). Higher magnification micrograph of the tracheal wall showing the mucosa (a) with it pseudostratified columnar epithelium (b) and lamina propria (c) of connective tissue. The arrow indicates the cilia located on the lumenal surface of the epithelium. Also shown is part of the submucosa (below and to the right of the dashed line), evidenced by the presence of seromucous glands (asterisk).