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PubMedDate not supplied

Catecholamine-containing cells of the taste buds in the tongue of the frog (Rana temporaria).

In a study of the epithelial layer and taste buds of the tongue of the frog using fluorescence, peculiar dumb-bell shaped cells were found in the taste buds of fungiform papillae and these showed a highly-positive reaction to catecholamines. Adrenergic nerve fibres were detected in the vessels of the taste bud and in the epithelium of the tongue. Under conditions of catecholamine deficiency produced by preliminary reserpinization of frogs a decrease in specific fluorescence of the cells and the nerves was observed.

Animals↗
PubMed1979

The distribution of alkaline phosphatase activity in normal and cross-species regenerated rat and mouse taste buds.

Alkaline phosphatase (ALK Pase) activity can be detected histochemically in the taste buds of rats but not mice. Since taste buds develop, regenerate and are maintained under the influence(s) of the sensory nerve it was decided to study cross-species regenerated buds of these two animals to determine whether the nerve also regulated ALK Pase development in taste cells. Grafts of rats sensory ganglion and mouse tongue or mouse ganglion and rat tongue were combined in the anterior chamber of the eyes of immunologically-deficient nude mice and the cross-species buds that developed at 35 days were examined histochemically for ALK Pase. The results revealed that the rat nerve did not cause ALK Pase to appear in any buds found in mouse tongue grafts and that mouse nerve could support buds containing ALK Pase in rat tongue tissue. Because the cross-species regenerated buds were histochemically characteristic of those normally found in rat or mouse tongue, there is no evidence that the foreign nerve altered gene expression for ALK Pase in the target organ, and the action of the nerve on gustatory epithelium appears to be that of activation and maintenance.

Alkaline Phosphatase↗
PubMed2001

A new gene (rmSTG) specific for taste buds is found by laser capture microdissection.

Getting pure populations of taste buds suitable for molecular analysis has hampered the characterization of genes specifically expressed in taste cells. To solve this problem, we prepared specific cDNA libraries from small numbers of taste cells and surrounding epithelium isolated by laser capture microdissection (LCM) and report the discovery of a rhesus monkey novel gene (rmSTG) expressed specifically in taste cells, as found by differential screening of the cDNA libraries and RNA in situ hybridization. RNA in situ hybridization shows the preferential expression of this gene in taste buds from circumvallate, foliate, and fungiform papillae of the tongue. RT-PCR and Northern analysis of RNA from different non-taste organs showed no expression, pointing to a very specialized function of the protein in taste cells. Analysis of extended cDNAs and genomic DNA showed two exons and one intron. Northern analysis of circumvallate papillae showed a transcript of 1.3 kb as established in the gene model. BLAST search analysis showed that the human homolog is localized in the recently completely sequenced HLA class I region of Chromosome 6p21 and is sublocalized to the main susceptibility region for psoriasis vulgaris. The predicted gene encodes a protein of 314 amino acids with an N-terminal signal peptide and cleavage site, suggesting a membrane-bound or secreted protein with an extracellular role in taste cell physiology. The monkey, human, and mouse STG proteins contain potential O-glycosylation sites and tandem repeats inside a region showing approximately 50% similarity with prion proteins.

Amino Acid Sequence↗
PubMed1993

Ion pathways in the taste bud and their significance for transduction.

Taste buds share a topology with ion-transporting epithelial and evidence now indicates that neural responses in rats to Na+ salts of differing anion are mediated by both transcellular and paracellular ion transport. Na+ exerts its effects mainly on the transcellular pathway. Neural responses to Na+ salts are enhanced by negative voltage clamp and suppressed by positive clamp in a manner indicating modulation of the apical membrane potential of receptor cells. Anion effects are mainly paracellular. Under zero current clamp increasing anion size reduces the neural response at constant Na+ concentration. Below about 50 mM this difference is entirely eliminated under voltage clamp. This suggests that paracellular transepithelial potentials normally create an anion difference. At higher concentrations the relatively high permeability of the paracellular shunt to Cl- permits sufficient electroneutral diffusion of NaCl below the tight junctions to stimulate cells that do not make direct contact with the oral cavity. In general, the sensitivity of a response to perturbations in the apical membrane potential indicates that some phase of Na+ salt taste transduction is accompanied by changes in an apical membrane channel conductance.

Animals↗
PubMed1986

Effect of mercury on the fish (Alburnus alburnus) chemoreceptor taste buds. A scanning electron microscopic study.

Taste buds (TBs) were investigated by scanning electron microscope on various parts of the oral cavity of the bleak. (Alburnus alburnus) after differently long exposures to mercury (300 micrograms/l Hg++). This low concentration of mercury did not result in lethal effect on the bleak even after 19 days long exposure, but produced morphological changes on the TBs, which showed duration dependency. The first sign of the morphological alteration on the TBs was observed after three days long exposure, when the microridge system of the epithelial cells became damaged and the mucus secretion increased on the apical surface of the TBs. On the TBs exposed for 10 days swollen microvilliar tips of the sensory cells could be observed besides the damage of the epithelial microridge system. On the TBs exposed for 19 days degenerative changes were detected on the microvilliar system of both the supporting and receptor cells. By this time completely degenerated TBs were frequently observed.

Animals↗
PubMed2004

Neurocalcin-immunoreactive neurons in the petrosal ganglion innervate the taste bud.

The distribution and origin of neurocalcin-immunoreactive (NC-ir) nerve fibers in the taste bud and carotid body were examined by an immunofluorescence method. In the circumvallate papilla of the tongue, NC-ir nerve fibers made subepithelial nerve plexuses and occasionally penetrated the taste bud. However, the carotid body was devoid of ir nerve fibers. In the petrosal ganglion, 32% of neurons were immunoreactive for NC. Such neurons were mostly medium-sized to large, and scattered throughout the ganglion. In the superior cervical and intralingual ganglia, numerous ir varicose fibers surrounded postsynaptic neurons. However, NC-ir could not be detected in cell bodies of these neurons. The retrograde tracing method indicated that NC-ir petrosal neurons innervated taste buds in the circumvallate papilla. NC-ir neurons may have a gustatory function in the petrosal ganglion.

Animals↗
PubMed1975

On the origin, development and probable functions of taste bud in the lip and bucco-pharyngeal epithelia of an Indian freshwater major carp, Cirrhinus mrigala (Hamilton) in relation to food and feeding habits.

1. Various developmental stages of taste bud have been observed in the fry, fingerling and adult of Cirrhinus mrigala (Hamilton). 2. The fries are zooplankton-feeders (carnivorous) and sight-feeders. Therefore, functional taste buds are absent in the lip and bucco-pharyngeal epithelia. Only formative stages of taste bud are present. Some epithelial cells aggregate together to form this structure which has no function in gustation. Moreover, the fires have low R. L. G. valle (0.71;..1.20) due to the carnivorous diet. 3. In the fingerling, the stages of elongation, differentiation and maturation of taste bund develop from the formative stage present in the fries in order to adjust to changed food and feeding habit. The value of R. L. G; (1.21...3.10) also increases. 4. Fully formed taste buds along with the stage of differentiation are found in the adult stage. The adult fish becomes herbivorous and bottom-feeder. Consequently, the value of R.L.G. 3.11...12) becomes highest in this stage.

Age Factors↗
PubMed1975

Ultrastructural alterations in rabbit taste buds induced by prolonged treatment with cycloheximide.

Prolonged administration of cycloheximide, an inhibitor of ribosomal protein synthesis, induces degeneration of rabbit taste bud cells: the degenerative changes resemble early changes in denervated taste buds. Our observations show that the pattern of degeneration is quite different in the three cell types of the taste buds. The earliest changes in type II and III cells are an increase in cytoplasmic filaments and extreme dilatation of rough endoplasmic cisternae. Profiles of dead type I and II cells vastly increase in number. Type I cells appear less affected by the drug and the only sign of degeneration was an increase in the number of autophagic vacuoles in their cytoplasm. There was no indication that degenerating type I cells undergo transformation to type II or III cells. These findings support our hypothesis that type I, II and III cells represent distinct cell types and do not undergo transformation to other types in the course of their life span.

Animals↗
PubMed1995

Cytochemical localization of guanylyl cyclase activity in rabbit taste bud cells.

Guanylyl cyclase activity was cytochemically demonstrated in rabbit foliate taste buds. The enzymatic activity was localized in the apical portion (microvilli and neck) of taste bud cells. Especially strong activity was observed on the microvillous membrane of type I (dark) cells and often on a blunt process of type III cells. The microvilli of type II (light) cells showed weak enzymatic activity. Considering that the apical portion of taste cells is a likely site of interaction between taste stimuli and the cells, the results support the idea that cyclic GMP is involved in taste transduction.

Animals↗
PubMed1987

Taste responses to amino acids from facial nerve branches innervating oral and extra-oral taste buds in the channel catfish, Ictalurus punctatus.

Electrophysiological recordings were obtained from two branches of the facial nerve innervating oral and extra-oral taste receptive fields, respectively, in the channel catfish, Ictalurus punctatus. The results indicate that taste buds innervated by the ramus ophthalmicus superficialis (ros), innervating taste buds on the nasal barbel, and the ramus palatinus (rp), innervating taste buds on the anterior palate, have similar chemical specificities for amino acids. Among the amino acids tested, the most stimulatory compounds for both the ros and rp were L-alanine and L-arginine, having estimated electrophysiological thresholds of approximately 10(-9) M. Dose-response functions for amino acid stimuli recorded from both the ros and rp were power functions extending over 5 log units of stimulus concentrations. The general similarity in the nature of the taste input from spatially distinct gustatory areas supports a chemotactic role of the facial taste system in the channel catfish.

Adaptation, Physiological↗
PubMedDate not supplied

[Evolution of the structural and cytochemical organization of the taste buds in vertebrates].

Ultrastructural and cytochemical organization of the receptors, supporting and basal cells of vertebrate taste buds are described. The receptor cells of all the vertebrates are characterized by single large microvillar process, well developed smooth endoplasmic reticulum and synaptic contacts with afferent and efferent nerve endings. A number of enzymes and acid mucopolysaccharides were demonstrated on the membrane of the microvillar process. At the synaptic area, AChE activity and monoamines are revealed. Besides, less numerous type of the receptor cells with several smaller microvillar processes are described in the taste buds. The supporting cells are characterized by numerous secretory granules and bundles of longitudinally oriented tonofibrils. The basal cells lie on the basal membrane and have no contact with the environment. Possible contribution of each type of the taste bud cells into gustation is discussed.

Acetylcholinesterase↗
PubMed1998

Scanning electron microscopy of denervated taste buds in hamster: morphology of fungiform taste pores.

BACKGROUND: Taste pores of fungiform papillae are critical for taste function. Taste nerve injury affects the pore, rendering it refractory to staining with vital dyes. Whether pores of denervated fungiform papillae disappear or undergo more modest structural changes to account for diminished staining was the subject of the present study. METHODS: The chorda tympani in the hamster was served unilaterally and the anterior tongue prepared for scanning electron microscopy after 31 days of survival. RESULTS: Taste pores were found on 92% of control fungiform papillae. They were round openings formed by the free margins of keratinocytes, and centered in hillock-shaped elevations of the papillary surface. Hillocks were encircled by an indentation which, in turn, was surrounded by a circular epithelial rim. These structures associated with fungiform pores distinguish pores on the anterior tongue from those on the posterior tongue. The pores led to a channel that penetrated into the papilla. The experimental side of the tongue had markedly fewer pores. Definitive pores were present on only 53% of denervated papillae. The papillae that lacked pores either exhibited a small hillock and a subtle depression in place of the pore, or had entirely flat apical surfaces. The denervated papillae that retained pores exhibited structural changes. The pores had smaller diameters and led to shallower channels than control pores. Moreover, these persistent pores were associated with hillocks, indentations and rims that were more variable and less distinct than those of control papillae. CONCLUSIONS: Pores of fungiform papillae in hamster are associated with specialized surfaces features of the papillary epithelium. Denervation results in changes that range from disappearance of the pores to their shrinkage and the atrophy of pore-associated epithelial structures.

Animals↗
PubMed1991

The distribution of fungiform papillae and taste buds on the human tongue.

Investigations on monkeys have shown that the application of the acidic dye Ponceau S red or the basic dye Alcian blue to the tongue surface facilitates identification of fungiform papillae and taste buds. Both of these dyes were now used in varying degrees of acidity on fixed and unfixed human cadaveric tongues in an attempt to determine the regional distribution of papillae and buds. Satisfactory staining was obtained with acidic Ponceau S red in 10% formalin and 10% trichloracetic acid (pH 2.5). For six tongues, the number of fungiform papillae ranged from 171 to 253 (mean 195) and these were located predominantly at the tip. Of the fungiform papillae, 67% had no staining of taste bud pores. The average number of visible taste pores on the other fungiform papillae was 3 (range 1-21). The correlation between the number of stained taste pores and underlying taste buds was confirmed using serial histological sections of 90 fungiform papillae. This work has shown that a mean of 193 taste buds are carried on fungiform papillae of the human tongue and that 87% of these are located in the anterior 2 cm.

Adolescent↗
PubMed1995

Light and electron microscopical demonstration of methylene blue accumulation sites in taste buds of fish and mouse after supravital dye injection.

Electron microscopical data regarding methylene blue staining of taste buds in the epithelia of the goldfish lip and the cirumvallate papilla of the mouse tongue after supravital dye application are presented for the first time. The ultrastructural details were compared with the corresponding light microscopical findings. The dye was applied in different concentrations by injection or in crystalline from directly to the surface of the tissues. Both methylene blue and tissue were simultaneously fixed by immersion in a paraformaldehyde-glutaraldehyde solution with the addition of phosphomolybdic acid. The ensuing dye precipitate was further stabilized by ammonium heptamolybdate. On the light microscopical level, the taste bud's receptive structures, i.e. the receptor area (fish) and the taste pit (mouse), exhibited the highest affinity for the dye. Additionally, the mucous material within the trenches around the circumvallate papillae in mice was intensely stained. On the electron microscopical level, the cationic phenothiazine dye bound to the receptor villi or to the mucus coating the receptive structures. In the case of higher dye concentrations, a staining of single taste bud cells took place starting apically and proceeding down to the base. Dye accumulations within the intercellular clefts between the epithelial cells or within other structures were observed only if the dye concentration was further increased. Since similar results were also obtained with the cationic phenazo dye Janus green, dye accumulation in the mucus covering the receptor villi may be representative of the general binding of organic cations, which are known to induce bitter taste sensations.

Animals↗
PubMed2005

The distribution of external taste buds in flower fish (Pseudophoxinus antalyae).

Purpose of this study was to determine the distribution of external taste buds of flower fish (Pseudophoxinus antalyae) on different body locations (lip, lateral, ventral and dorsal areas, dorsal-pelvic-pectoral-anal fins). In this species, it was found that the density of taste buds was greater on lip epithelium than that of lateral (between pectoral-anal, anal-caudal fins), ventral (between pelvic and anal fins) and dorsal (close to the head) locations. It was observed that the shape of taste bud changed depending upon the epithelium thickness and it was found that some of these structures protruded towards to the exterior of epithelium.

Animals↗
PubMed1995

Three-dimensional structure of the gustatory cell in the mouse fungiform taste buds: a computer-assisted reconstruction from serial ultrathin sections.

Taste buds in fungiform papillae of the mouse were examined with transmission electron microscopy and computer-assisted, three-dimensional reconstruction from serial ultrathin sections. In accord with observation by Murray (1971), four distinct cell types, type I, II, III and basal cells, were identified. Of these, only the type III cell made synaptic contacts with nerve terminals and contained both small, clear vesicles and dense-cored granules. The former vesicles were synaptic-type and accumulated in the cytoplasm just below the synaptic in membrane thickenings. This finding clearly indicates a sensory function for the type III cell. One to three type III cells were identified within a taste bud. The type III cell had at most eight synapses with nerve terminals. One nerve fiber making two synapses with the type III cell was occasionally observed in its terminal region.

Animals↗
PubMed1978

Intracellular characteristics and responses of taste bud and lingual cells of the mudpuppy.

Intracellular recordings of membrane potentials of mudpuppy lingual cells were made with micropipette electrodes. Three types of cells were distinguished by their responses to chemical stimulation. Surface epithelial (SE) cells outside of taste buds responded with large membrane potential and resistance changes to a variety of stimuli representing the four taste qualities. Salts and acids evoked particularly large potential changes, and MgCl2, acids, and quinine greatly increased the membrane resistance. One type of taste bud cell (TB-1) was characterized by large depolarizations to K salts, and the other type of taste bud cell (TB-2) characteristically hyperpolarized to MgCl2, acid, and sugar solutions. Membrane resistance changes accompanying TB-1 and TB-2 cell responses were relatively small compared to those of SE cells. Electrotonic coupling was observed between pairs of SE and TB-2 cells but not for pairs of TB-1 cells nor cells of different types. After recording cell responses, dye-marking allowed verification of results in situ and histologically. From the identification of cells in section, it is hypothesized the TB-1 and TB-2 cells correspond to light and dark cells, respectively. Responses of TB-1 cells imply a taste receptive function; wheras TB 2-cell responses suggest secretory, supportive, and (or) receptive functions. Factors affecting cellular characteristics, non-taste bud cell responsiveness, response mechanisms, and function of electrotonic coupling are discussed in relation to taste reception.

Acids↗