Taste bud distribution in the rat pharynx and larynx.

The present study evaluated the number and distribution of taste buds in the rat pharynx and larynx using light microscopic techniques. The average number of taste buds in this region was 141.9 (S.D. = 29.4, n = 10). Pharyngeal and laryngeal taste buds could be grouped into three subpopulations: those associated with laryngeal structures (LA), the nasopharynx (NP), or the palatopharyngeal eminence (PE). Laryngeal taste buds were most numerous (mean = 103.2, S.D. = 23.6). They were observed on the laryngeal surface of the epiglottis and extended caudally along the aryepiglottic folds, reaching peak density at the caudal extreme of the folds. Further caudally, when the larynx and rostral esophagus separated, taste bud density decreased sharply. Fewer taste buds were associated with the NP (mean = 31.9, S.D. = 13.7) or PE (mean = 6.8, S.D. = 4.0) and taste bud density in these subpopulations peaked at the anterior border of the nasopharyngeal hiatus. Taste buds in the rat larynx and pharynx account for 10% all taste buds in this species, a proportion similar to that accounted for by taste buds on the soft palate. Taste buds in this region appear to be ideally situated for protecting the airway during accidental aspiration of food or fluids. Most pharyngeal and laryngeal taste buds are unlikely to be involved in triggering normally occurring swallows, although they could be stimulated as the bolus is propelled from the oral cavity to the esophagus.