Pituitary adenylatecyclase-activating polypeptide-immunoreactive nerve fibers in the rat epiglottis and pharynx
Mitsuhiro KanoYoshinaka ShimizuYujiro SuzukiYusuke FurukawaHiroko IshidaMiho OikawaHiroyasu KanetakaHiroyuki IchikawaToshihiko Suzuki
9
Citation
25
Reference
10
Related Paper
Citation Trend
Keywords:
Epiglottis
Glossopharyngeal nerve
Taste bud
Taste bud
Glossopharyngeal nerve
Lingual papilla
Ampulla
Cite
Citations (25)
Epiglottal taste buds of the sheep increase in number during development, and continue to increase until the epiglottis has reached its adult size. However, since the increase in taste bud numbers is paralleled by increase in the surface area of the epiglottis, the density of taste buds decreases progressively in the fetus and newborn. After birth the density remains relatively constant. From examination of the morphological stages of epiglottal taste bud development, we conclude that taste buds are originally produced by de novo formation, but that further increase in numbers is effected by division of existing, developing taste buds. Because of the large number of taste buds, and the maintenance of their density on the epiglottis, it is concluded that they have an important functional role in upper airway protective reflexes.
Epiglottis
Taste bud
Cite
Citations (58)
Glossopharyngeal nerve
Oculocardiac reflex
Cite
Citations (0)
The laryngeal surface of the epiglottis contains a large number of taste buds. Some investigators have considered that epiglottal taste buds may have a function as chemical sensors to initiate the reflex reaction to protect the airway, but little is known about their functional role. As an initial step in a study to understand the function of laryngeal taste buds, the surface morphology, number, and location of rat epiglottal taste buds throughout development were observed by scanning electron microscopic techniques. The diameters of epiglottal taste buds were about 1/3 the size of lingual taste buds. Taste pores were found among most of the epiglottal taste buds. Microvilli projected from the taste pores. A rapid increase in the number of epiglottal taste buds occurred at about 12 weeks of age, and a rapid decrease occurred after about 30 weeks of age. The maximal number of epiglottal taste buds was counted during the period between about 12-20 weeks of age. This period of age may coincide with a peak of rat developmental stages. High-density regions of taste buds on the laryngeal surface of the epiglottis were located around the base of epiglottis. Since epiglottal taste buds seem to be in an optimal location for contact with food, it is suggested that they have an important role as a chemical receptor to protect the upper airway.
Epiglottis
Taste bud
Bitter Taste
Taste receptor
Cite
Citations (1)
We investigated the positioning of the epiglottis in the pharyngo-laryngeal region and the distribution of taste buds on the epiglottis in the rat and house shrew, animals which have different feeding habits. In the fixed samples of both species, when the mouth was closed or slightly opened, the epiglottis was found to protrude into the nasopharyngeal hiatus above the soft palate. But it retracted from its position when the mouth was widely opened. In omnivorous rats (n = 6), the mean number (mean density ± s. d.) of taste buds was 52 (12.6 ± 2.2/mm2) on the laryngeal surface but only 4 (1.3 ± 1.0/mm2) on the oral surface. The three-dimensional view was reconstructed from serial sections. The taste buds were distributed most densely close to the caudal base and became fewer toward the more rostral tip. In insectivorous house shrews (n = 2),4 taste buds on average were found only on the laryngeal surface of the epiglottis. Epiglottal taste buds may work as chemosensory detectors to initiate the reflex reaction to protect the airway from oral substances during swallowing and drinking.
Epiglottis
Taste bud
Shrew
Soft palate
Cite
Citations (8)
The effect of glossopharyngeal nerve transection on the taste buds of the rat vallate papilla was examined by using the method of DNA nick-end labeling (TUNEL) and standard electron microscopic technique at 1, 3, 5, 7, 9 days after denervation. In general, the number and size of taste buds decreased as more days passed after denervation. They started decreasing on day 3 post denervation and virtually all taste buds were disappeared on day 9 post denervation. In studies using TUNEL method, TUNEL postive cells markedly increased in their numbers one day post denervation, as compared with controls. The number of apoptotic taste bud cells per taste bud profile was averaged to be 0.64 and 0.44 for day 1 and 3 post denervation, respectively, whereas it was 0.10 in controls. In electron microscopy, apoptotic cells were identified by the presence of condensed and fragmentary nuclei in a cytoplasm, which resulted in increased density. In control rats, only few apoptotic cells were found. On days 1 and 3 post denervation, nerve fibers almost disappeared from the taste buds and some apoptotic cells were apparent. On days 7 and 9 post denervation, a few taste bud cells were still present in the epithelium of the bottom of the trench wall of the vallate papilla and most of them showed apoptotic changes. The results indicate that the death of taste bud cells in normal conditions is controlled by apoptosis and the decrease and disappearance of taste buds after denervation is also caused by apoptosis of taste bud cells.
Taste bud
Lingual papilla
Glossopharyngeal nerve
Cite
Citations (0)
The neurosurgical treatment of glossopharyngeal neuralgia includes microvascular decompression or rhizotomy of the nerve. When considering open section of the glossopharyngeal nerve, numerous authors have recommended additional sectioning of the 'upper rootlets' of the vagus nerve because these fibers can occasionally carry the pain fibers causing the patient's symptoms. Sacrifice of vagus nerve rootlets, however, carries the potential risk of dysphagia and dysphonia. In this study, the anatomy and physiology of the vagus nerve rootlets are characterized to provide guidance for surgical decision-making. Twelve patients who underwent posterior fossa craniotomy with intraoperative electrophysiological monitoring of the vagus nerve rootlets were included in this study. In the 7 patients with glossopharyngeal neuralgia, the clinical outcomes and complications were further analyzed. In half of the patients, electrophysiological data demonstrated pure sensory function in the rostral rootlet(s) of the vagus nerve and motor responses in its caudal rootlets. This orientation of the vagus nerve, with some pure sensory function in its most rostral rootlet(s), was defined as Type A. In the other half of patients, all vagus nerve rootlets (including the most rostral) had motor responses. This was defined as Type B. The surgical strategy was guided by whether the patient had a Type A or Type B vagus nerve. For those with Type B, no vagus nerve rootlets were sacrificed. None of the patients with glossopharyngeal neuralgia developed any permanent neurological deficits. We recommend intraoperative electrophysiological testing of the vagus nerve rootlets. If the testing reveals motor innervation in the rostral vagal rootlet (Type B), that rootlet may be decompressed but should not be sectioned to avoid a motor complication. Patients with pure sensory innervation of the rostral rootlet(s) (Type A) can have decompression or section of those rootlets without complication.
Glossopharyngeal nerve
Accessory nerve
Cranial nerves
Cite
Citations (9)
This investigation aimed to demonstrate age-related changes of taste buds on the human epiglottis using histomorphometrical analysis.Histological observation and measurement of taste bud density were performed on oral and laryngeal surfaces of 237 human epiglottises (138 male and 99 females). The cases were divided into two age groups: 67 cases in the younger group, for subjects aged 10-39 years and 170 cases in the older group, for those aged 70-98 years. Each epiglottis was investigated at the upper and middle height levels.The mean density of taste buds significantly decreased on the laryngeal surfaces in the older group. Most taste buds were present in the upper height level on the laryngeal surfaces which were covered with thin and flat stratified squamous epithelium. The covering epithelium revealed developed epithelial ridges on the oral surfaces without taste buds. These results suggest a relationship between the existence of taste buds and the thickness of the covering epithelium.The presence of taste buds in the epiglottises of elderly people was demonstrated. In addition, the decrease of these taste buds with advancing age was clarified.
Epiglottis
Taste bud
Age groups
Taste disorder
Stratified squamous epithelium
Cite
Citations (28)
The innervation pattern by primary afferent nerve fibres and the neurotrophic effect on taste cells were investigated in the guinea pig vallate taste bud by means of glossopharyngeal neurectomy and horseradish peroxidase (HRP) or wheat germ agglutinin-horseradish peroxidase (WGA-HRP) tracing. In the glossopharyngeal neurectomy study, taste buds in the vallate papillae of adult guinea pigs were denervated by unilateral resection of the right glossopharyngeal nerve. Denervated animals were killed on days 1, 3 and 5 and weeks 1-9, 12 and 24 postneurectomy. The results showed that, on the denervated side, the taste buds decreased significantly in number during the 1st 2 wk, and disappeared completely by wk 3; no mature taste buds were present even 24 wk after neurectomy. This suggests that the vallate taste buds disappear in the absence of the glossopharyngeal nerve. In the neural tracing study, HRP or WGA-HRP was injected into the proximal end of the right glossopharyngeal nerve, near the jugular foramen. After a survival time of 24 h, the vallate papillae were sectioned and examined by light and electron microscopy. Light microscopy revealed that the HRP or WGA-HRP-labelled fibres innervated the vallate taste buds of the injected side. Most of the taste cells in the buds were labelled with HRP or WGA-HRP reaction products from the basal to the apical region. At the ultrastructural level, the reaction products were confined to the cytoplasm of the labelled cells, which were identified as type I, II and III cells, but not basal cells. Labelled intragemmal nerve profiles were seen among the taste cells. No synapse formation was seen with nerve profiles abutting on type I and II cells, whereas on certain type III cells, typical synapses were formed. We conclude that both the right and left vallate papilla in the guinea pig are unilaterally innervated by the glossopharyngeal nerve without cross-innervation.
Glossopharyngeal nerve
Lingual papilla
Taste bud
Horseradish peroxidase
Neurectomy
Cite
Citations (13)