ANATOMY OF THE OLFACTORY SYSTEM
In Figure 12.1, a microscopic cross-section of the olfactory region offers insights into the intricate structure of olfactory receptor cells. Each cell comprises a cell body with two extending nerve fibers - one functioning as a dendrite and the other as an axon.
Examining this microscopic view, we observe the dendritic process of the olfactory cell extending beyond the olfactory region membrane, nestled within crevices between sustentacular cells. These sustentacular cells play a vital role in providing substantial support to the dendritic processes, effectively shielding the olfactory cell bodies from direct exposure to the nasal cavity. Notably, within this location, hair-like structures known as olfactory cilia project into the nasal cavity from the olfactory vesicles, which represent the expanded parts of dendrites. Typically covered with a thin secretion from Bowman's glands (subepithelial glands), these cilia play a crucial role in the olfactory process. The ducts of Bowman's glands traverse through the epithelium to reach the surface, ensuring a constant supply of secretions that refresh the thin layer of fluid bathing the olfactory hairs on the surface of the olfactory region.The mechanism of sniffing becomes integral in this process, facilitating the back-and-forth movement of air. This action increases the likelihood of the substance being smelled going into solution, acting as the stimulus for the subsequent transmission of impulses to the brain. The coordinated activity of the olfactory cells' axons, joining with others to form fibers and branches of the olfactory nerves, further contributes to the efficient transmission of olfactory signals. Additionally, the paragraph underscores the importance of basal cells, which undergo division and differentiation into sustentacular or olfactory cells, acting as a protective mechanism against the potential loss of smell resulting from nasal mucosal diseases (Figure 12.1).
12.3