Olfactory epithelial cells are modified neurons interspersed within the olfactory epithelium. The cell bodies of these olfactory neurons reside within the epithelium and have cilia that project onto the surface. These cilia are not visible in light microscope. The axons of these neurons extend to the olfactory bulb located within the cranial cavity.

The epiglottis is a large, flat flap cartilage that controls entry to the trachea. During breathing, the epiglottis is in an upright position and keeps the entry to the trachea open. During swallowing, the epiglottis covers the entry to the trachea, redirecting food to the esophagus.

The inside of the trachea is lined with pseudostratified ciliated columnar epithelium, which is continuous with the larynx. This epithelial layer has mucus producing goblet cells that are only visible at high magnification. Underneath the epithelium is the lamina propria that contains submucosal glands that also produce mucus. The next layer is the hyaline cartilage, followed by the smooth muscle layer.

Source: https://uta.pressbooks.pub/histology/chapter/respiratory-system/