Olfactory mucosa, nasal cavity, human, Azan ×375.
At this higher magnification, it is possible to distinguish in a general way the three principal cell types of the olfactory epithelium on the basis of nuclear location and appearance, as well as by certain cytoplasmic characteristics. For example, the nuclei of the supporting cells (SC ) are relatively dense and are located closest to the epithelial surface. They are arranged in an almost discrete single layer. The supporting cell has a cylindrical shape and extends from the basement membrane through the full thickness of the epithelium. Immediately beneath this layer are the cell bodies of the olfactory receptor cells (OC ). They lie at different levels within the thickness of the epithelium. Careful examination of the nuclei of these bipolar neuronal cells reveals that they contain more euchromatin than the nuclei of the supporting cells and often exhibit several nucleoli. In this preparation, the nucleoli appear as small round red bodies. In some cases, particularly when there is shrinkage, the thin tapering dendritic process that extends to the olfactory surface may be observed. Similarly, an axonal process may sometimes be observed extending basally. The basal cells (BC ), the least numerous of the principal cell types, are characterized by their small round nuclei and scant cytoplasm. They are irregularly spaced and lie in proximity to the basement membrane. Note that the olfactory mucosa in contrast to respiratory mucosa lacks goblet cells.
The lamina propria contains numerous blood vessels (capillaries [C ], veins [V ]), lymphatics, olfactory nerves (N ), and olfactory (Bowman’s) glands (BG ). The Bowman’s glands are branched tubuloalveolar structures. They exhibit a very small lumen (arrows). The duct elements extend from the secretory portion of the gland beginning in close proximity to the overlying epithelium (arrowhead) and pass directly through the epithelium to deliver their secretions at the surface. The ducts are very short, making it difficult to identify them. The very thin axonal processes (AP ) of the olfactory cells are sometimes evident within the lamina propria prior to being ensheathed by Schwann cells to form the prominent olfactory nerves. The nuclei present within the olfactory nerves represent Schwann cell nuclei (ScC ).
KEY A, artery AP, axonal process BC, basal cells BG, Bowman’s glands C, capillary EB, ethmoid bone ES, ethmoid sinus N, olfactory nerves OC, olfactory cells OEp, olfactory epithelium OM, olfactory mucosa REp, respiratory epithelium SC, supporting cell nuclei ScC, Schwann cell nuclei V, vein arrows, lumina of Bowman’s glands arrowhead, duct of a Bowman’s gland entering epithelium
The larynx is the passageway for air between the oropharynx and the trachea that functions in the production of sound. It consists of a carti-laginous framework to which both extrinsic and intrinsic muscles are attached and a mucosal surface that varies in character from pseudos-tratified to stratified squamous in regions subject to abrasion by the air stream. The muscles move certain cartilages with respect to others, thus increasing or decreasing the opening of the rima glottis and increasing or decreasing the tension on the vocal folds (cords). In this way, vibrations of different wavelengths are generated in the passing air, and sound is produced.
Larynx, monkey, H&E ×15.