Cholinergic innervation of the tongue of the one humped camel, Camelus dromedarius

Distribution of adrenergic and cholinergic nerve profiles in the tongue of camel has been studied by histochemical methods. The tongue is richly innervated by cholinergic nerve profiles as is evidenced by the presence of numerous nerve fibres at different levels. There is noted strong cholinesterase positive reaction close to the lateral border of the circumvallate papillae (in the region of the taste buds) and the upper border of the fungiform papillae. Numerous nerve fibres have been observed in the connective tissue core of all the lingual papillae. Adrenergic nerve terminals could not be observed in the taste buds though numerous adrenergic nerve fibres could be seen in and around the blood vessels. Rich cholinergic innervation of the blood vessels has also been noted in the tongue.     

Neural control of ectopic filiform spines in adult tongue

The tongue surface directly above a fungiform taste bud is flat, thinly keratinized, and free of filiform spines. We examined fungiform papillae in serial sections of rat and gerbil tongues after unilateral transection of the chorda-lingual nerve had caused many fungiform taste buds to degenerate. Such empty fungiform papillae often formed a solitary keratinized outgrowth that closely resembled the spine of an ordinary filiform papilla. By six months an ectopic spine was found on 61% of empty fungiform papillae, but never on fungiform papillae that contained a taste bud. Experimental innervation of the tongue reduced the incidence of ectopic filiform spines in proportion to the cross-sectional area of the trigeminal nerve branches tested (the mylohyoid nerve, the lingual nerve, lingual + mylohyoid or lingual + auriculotemporal nerves). The chorda tympani nerve was 60 times more effective than trigeminal nerves in preventing ectopic filiform spines. We suggest that positive and negative trophic actions are normal characteristics of taste axons, for they promote the formation of taste buds and prevent the expression of ectopic filiform spines. By preventing the outgrowth of ectopic spines on fungiform papillae, taste axons maintain a thinly keratinized apical surface that can be breached by the taste receptor cells.     

The nature of the substance P-containing nerve fibres in taste papillae of the rat tongue

The nature of the association of substance P (SP) with taste buds in the rat tongue was investigated by immunohistochemical and radioimmunoassay techniques. Both the circumvallate and fungiform papillae were found to receive a rich innervation by substance P-containing fibres. Although these fibres were closely associated with the taste buds in these structures, they assumed a perigemmal rather than an intragemmal location. Bilateral lesions of the glossopharyngeal nerve resulted in the depletion of taste buds from the vallate papilla and a large reduction in substance P immunoreactive fibres in this area. Lesions of the chorda tympani, which led to the degeneration of taste buds in fungiform papillae, had no effect on the immunohistochemical appearance of substance P in these papilla or on the substance P levels in the anterior part of the tongue. Lesions of the mandibular division of the trigeminal nerve or neonatal capsaicin treatment had no effect on the structural integrity of taste buds in fungiform papillae but led to the depletion of substance P-immunoreactive fibres from these papillae. Both of these procedures caused a 71% reduction in the substance P content of the anterior tongue, ipsilaterally after the nerve lesion and bilaterally after capsaicin treatment. The results are discussed in relation to the possible functional role of substance P-containing fibres within nerves supplying taste structures of the tongue.     

Neonatal chorda tympani transection permanently disrupts fungiform taste bud and papilla structure in the rat

The present report examined the morphology of fungiform papillae in adult rats that received bilateral chorda tympani transection at 10 days of age. Tongue tissue was examined using surface-structure analysis. Counts were made of fungiform papillae with a pore, fungiform papillae with no pore and fungiform papillae with a keratinized conical surface; a feature referred to as "filiform-like. " Neonatal chorda tympani nerve transection resulted not only in a loss of taste buds but also in a permanent loss in numbers of fungiform papillae. Compared with an average of 152 fungiform papillae in sham-operated control rats, there was an average of only 54 fungiform papillae after neonatal chorda tympani transection. Nearly 80% of these fungiform papillae in neonatal chorda tympani transected rats were filiform-like. No filiform-like papillae were noted in sham-operated rats. These results suggest that the chorda tympani nerve is necessary during an early postnatal period of development to maintain normal fungiform papillae morphology.     

Spatial distribution of rat fungiform papillae

The objective of this study was to determine the spatial distribution of fungiform papillae on the rat's tongue. Since each fungiform papilla in the rat has a single taste bud, the spatial distribution of fungiform papillae is equivalent to the location of taste buds on the anterior tongue. A mean total number of 187 fungiform papillae per tongue were found which were about equally divided between the two lateral halves of the tongue. Over 50% of the total number of fungiform papillae were located on the tongue tip for an average density of 3.4 papillae/mm², while the dorsal surface of the tongue had an average density of 1.3 papillae/mm² of tongue surface. Papillae were absent on the dorsal midline, but a paracentral line of papillae running from anterior to posterior was a consistent finding. Though not identical, the distribution of papillae was essentially the same on different tongues. The functional significance of the papilla distribution is not understood, but electrophysiological experiments show evidence of neural interaction of papillae which are clustered together. The distribution of papillae and the distribution of nerve fibers which innervate them must be evaluated together in order to appreciate the significance of the distribution of fungiform papillae and their associated taste bunds.     

Organization of geniculate and trigeminal ganglion cells innervating single fungiform taste papillae: a study with tetramethylrhodamine dextran amine labeling.

Single gustatory nerve fibers branch and innervate several taste buds. In turn, individual taste buds may receive innervation from numerous gustatory nerve fibers. To evaluate the pattern of sensory innervation of fungiform papilla-bearing taste buds, we used iontophoretic fluorescent injection to retrogradely label the fibers that innervate single taste papillae in the hamster. For each animal, a single taste papilla was injected through the gemmal pore with 3.3% tetramethylrhodamine dextran amine. Fungiform papillae either at the tongue tip (0.5-1.5 mm from the tip) or more posteriorly (1.5-3.0 mm from the tip) were injected. After one to seven days survival, the geniculate and trigeminal ganglia and the tongue were sectioned and examined for labeled cells and fibers, respectively. Analysis of the number and topographic distribution of geniculate cells innervating single taste papillae, shows that: (i) 15 +/- 4 (S.D.) ganglion cells converge to innervate a single fungiform taste bud; (ii) more ganglion cells innervate anterior- (range: 13-35 cells) than posterior-lying buds (range: five to 12 cells), which, in part, may be related to bud volume (microm3); and (iii) ganglion somata innervating a single taste bud are scattered widely within the geniculate ganglion. Analysis of labeled fibers in the tongue demonstrated that two to eight taste buds located within 2 mm of the injected taste bud share collateral innervation with the injected taste bud. Since all buds with labeled fibers were located in close proximity (within a 2-mm radius), widely dispersed geniculate ganglion cells converge to innervate closely spaced fungiform taste buds. Trigeminal ganglion (mandibular division) cells were also labeled in every case and, as with the geniculate ganglion, a dispersed cell body location and collateralization pattern among papillae were observed. This study shows that iontophoresis of tetramethylrhodamine dextran amine, selectively applied to individual peripheral receptor end-organs, effectively locates sensory ganglion cells in two different ganglia that project to these sites. Moreover, the marker demonstrates collateral branches of sensory afferents associated with the labeled fibers and the nearby receptor areas innervated by these collaterals. The labeling of single or clusters of receptor cells, as well as identified sensory afferents, affords future possibilities for combining this technique with immunocytochemistry to establish the relationships of innervation patterns with neurotransmitters and neurotropic substances within identified cells.     

Scanning Electron Microscopic Study of the Human Fungiform Papillae

Human lingual mucosa reveals a highly differentiated papillary organization. The fungiform papillae are grouped as gustatory papillae as they contain taste buds and function as sensory end organs. Taste pores, the surface openings of the taste buds, play important roles both in preneural and neural phases of taste perception by receiving external chemical stimuli and its transduction. Scanning electron microscopy [SEM] of the dorsal lingual surface was used to study the morphology and ultrastructure of the fungiform papillae in human. The lingual samples were prepared from 20 unfixed cadavers at Burdwan Medical College and after proper processing they were examined under SEM at the University of Burdwan. The results demonstrated that these gustatory structures were dome shaped with round base and their diameters were approximately 300 – 800 µm. They were surrounded by shallow circular furrow with small mucosal pad encircling the furrow. The study verified that the covering epithelium of the fungiform papillae is stratified squamous type and frequent desquamation of lining cells was also noticed. Elevated cell margin with distinct intercellular borders were evident in the lining epithelium. Single or multiple circular taste bud pores opened on the upper surface of some of these papillae while in others taste pores were absent. Taste bud pores had diameter of about 3-6 µm. On higher magnification SEM images established the presence of lattice patterned microridges over the epithelial cell surfaces. Within these microridges microgrooves or mucous pits were observed. These observations were related with specific mechanical and gustatory roles.     

Expression of ATP-gated P2X3 receptors in rat gustatory papillae and taste buds

It has recently become evident that ATP and other extracellular nucleotides could play an important role in signal transductions. ATP mediates excitatory signaling by means of P2X receptors. P2X3, one of its subtypes, a membrane ligand-gated ion channel, is strongly expressed in peripheral sensory neurons. The aim of the present study was to examine the distribution of nerve fibers expressing P2X3 receptors in taste buds in the gustatory papillae and soft palate of rats by immunohistochemistry. We found that the fluorescence ATP marker quinacrine stained subsets of taste bud cells. Numerous nerve fibers innervating taste buds were intensely immunostained with the P2X3 receptor antibody. These nerve fibers ascended among intragemmal cells and terminated just below the taste pores. In order to examine whether P2X3 receptors are involved in signal modulation within taste buds, we used fluorescent double stainings to analyze the distribution of P2X3 receptors and their relationship to alpha-gustducin immunopositive taste receptor cells. Many varicose nerve fibers expressing P2X3 receptor-immunoreactivities were entangled with alpha-gustducin-immunopositive taste receptor cells and ended closely below the taste pores. In fungiform papillae, nerve fibers expressing both P2X3 receptors and PGP 9.5 were observed. In contrast, only PGP 9.5 immunoreactive nerve fibers were recognized in filiform papillae. These results suggest that P2X3 receptors might be involved in taste transmission pathways within taste buds. ATP may act as a neurotransmitter, co-transmitter, or neuromodulator at P2X3 receptors to generate activating gustatory nerve fibers.     

Distribution of taste buds on fungiform and circumvallate papillae of bovine tongue

The distribution of taste buds on the fungiform and circumvallate papillae of the cow tongue has been determined. The two tongues studied were from Holstein-Friesian cows four to six years of age; they contained 14,765 and 21,691 taste buds, respectively. The tip of the tongue is well supplied with fungiform papillae, and the posterior portion contains the circumvallate papillae. The midportion of the tongue contains relatively few taste papillae. The fungiform papillae contained 1,580 and 1,838 taste buds on the two tongues, respectively, and the circumvallate papillae were estimated to contain 13,185 and 19,853 taste buds. The highest concentration of taste buds therefore occurs in the circumvallate papillae; these relatively few papillae contain approximately 90% of the taste buds. On a circumvallate papilla, taste buds are found only on the papillary sidewall, with none either on the apical surface of the papilla or on the outer wall of the moat.     

Long-term effects of gustatory neurectomy on fungiform papillae in the young rat

Recent evidence from mature hamster fungiform papillae indicates that following denervation taste buds are present from 21 to 330 days in the absence of discernible intragemmal nerve fibers. In contrast, most prior taste bud degeneration studies focused on shorter survival times. The present inquiry in young rats examined the issue of postneurectomy buds, in which regeneration of the resected chorda tympani or facial nerves was prevented and anterior tongue tissue examined over a range of relatively long survival times (30-90 days). Conditions for observing potential taste buds used three histologic stains and a definition of the taste bud not necessarily requiring pore identification. In each case, serial section examination of the anterior-most 2-3 mm of lingual epithelium revealed 29-56 bud-containing fungiform papillae on the unoperated side. In contrast, ipsilateral to the neurectomy, only zero-7 medially-placed, mature-looking buds were observed per case, as well as zero-3 more laterally situated fungiform papillae containing small clusters of cells in basal epithelium that lacked the vertical organization and cytoplasmic staining intensity of mature taste buds. These cell aggregates were distributed evenly across survival time and stain used. Therefore, in young rats following gustatory neurectomy, longer survival times, per se, would not appear to be a prerequisite for sustaining fungiform taste buds. The appearance of "midline" buds postsurgery may be attributed to either normal contralateral or a net bilateral innervation, and/or ipsilateral denervation and bud loss inducing neural sprouting from the contralateral side.     

Scanning electron microscopy study of the tongue and lingual papillae of the California sea lion (Zalophus californianus californianus)

We observed the three-dimensional structures on the external surface and the connective tissue cores (CTCs) of the California sea lion (Zalophus californianus californianus), after exfoliation of the epithelium of the lingual papillae (filiform, fungiform, and vallate papillae), using scanning electron microscopy (SEM) and conventional light microscopy. Macroscopically, the tongue was V-shaped and its apex was rounded. At the posterior area of the tongue, five vallate papillae were arranged in a V shape. In the epithelium, numerous taste buds were distributed on the top of the vallate papillae. On the dorsal surface from the apex to the boundary between the anterior and posterior tongue, filiform papillae were densely distributed. The CTCs of the filiform papillae consisted of a main protrusion (primary core) and many small cores (secondary cores). From the apex to the anterior one-third of the tongue, dome-like fungiform papillae were densely distributed, whereas fewer were located at the posterior two-thirds of the tongue. Several taste buds were found in the epithelium on the fungiform papillae. The size of the filiform papillae gradually increased from the apex to the boundary between the anterior and posterior tongue. At the lingual radix, the conical papillae, which were bigger than any filiform papillae, were densely distributed. The morphological characteristics of the tongue of the California sea lion appear to have been transformed to adapt to an aquatic environment; however, they possess some structures similar to those of land mammals.     

Development of fungiform papillae: patterned lingual gustatory organs

The fungiform papilla is a gustatory organ that provides a specific tissue residence for taste buds on the anterior tongue. Thus, during development there must be a progressive differentiation to acquire papilla epithelium, then taste cell progenitor epithelium, and finally taste cells within the papilla apex. Arranged in rows, the patterned distribution of fungiform papillae requires molecular regulation not only to induce papillae, but also to suppress papilla formation in the between-papilla tissue. Intact sensory innervation is not required to initiate papilla development or pattern. However, members of several molecular families have now been identified with specific localization in developing papillae. These may participate in papilla development and pattern formation, and subsequently in taste progenitor and taste cell differentiation. This review focuses on development of fungiform papillae in embryonic rat and mouse. Basic morphology, cell biology and molecular phenotypes of developing papillae are reviewed. Regulatory roles for molecules in several families are presented, and a broad schema is proposed for progressive epithelial differentiation to form taste cell progenitors in parallel with the temporal course, and participation of lingual sensory innervation.     

Quantitative study of fungiform papillae and taste buds on the cat's tongue

The number of fungiform papillae has been counted on the tongues of six adult cats and of kittens both at birth and aged 2 and 4 months. Papillae were sampled from different regions of the tongue, and their size and the number of taste buds they contained were determined using histological sections taken parallel to the tongue surface. There were approximately 250 fungiform papillae on the tongues of the adult cats, the papillae were most numerous at the tip of the tongue, and there was no significant difference between the number of papillae on each side. The size of the papillae increased from a mean maximum diameter of 0.28 mm at the tip of the tongue to 0.48 mm at the back; the mean number of taste buds increased correspondingly from 6.9 to 16.6. The kitten tongues had a number and distribution of fungiform papillae similar to that found in the adults. In the neonate, papillae were smaller and contained fewer taste buds; these parameters increased with the corresponding increase in tongue size in the 2- and 4-month-old kittens.     

Gustatory responsiveness of fibers in the hamster glossopharyngeal nerve

1. Mammalian taste receptors are distributed within separate subpopulations, innervated by branches of cranial nerves VII, IX, and X. Most gustatory electrophysiology has focused on input from the fungiform papillae on the anterior portion of the tongue, carried by the chorda tympani branch of the VIIth nerve. However, only a small percentage of the taste buds are located in the fungiform papillae (approximately 18% in the hamster). There have been no studies on the hamster's IXth nerve, which innervates greater than 50% of its taste buds, and most other studies of IXth nerve function have employed only whole-nerve recording. 2. Action potentials were recorded from 83 individual fibers in the IXth nerve of the hamster. Stimuli were five concentrations each of sucrose, NaCl, HCl, and quinine hydrochloride (QHCl), all presented to every fiber at 37 degrees C. Responses were quantified as the number of impulses in 10 s minus the preceding 10 s of spontaneous activity. 3. Across these concentration series, HCl and QHCl were by far the most excitatory stimuli, with mean responses across all cells three to four times greater than those evoked by sucrose or NaCl. The order of effectiveness of the stimuli was H greater than Q much greater than N greater than S. 4. Of the 83 fibers, 56 were stimulated via the foliate papillae and 27 via the single vallate papilla. No fibers responded to both of these fields. There were generally no differences in the sensitivity of these two subpopulations of taste buds, except that QHCl was more effective when applied to the foliates. 5. A "total" response measure was derived by summing the excitatory responses to each stimulus across the entire concentration series. The fibers were then classified according to the best total response, resulting in 52 HCl-, 19 QHCl-, 8 sucrose- and 4 NaCl-best cells. Considering the slope of the concentration-response functions as a criterion for classification produced very similar results. The fiber classification varied somewhat with concentration, with more fibers categorized as HCl- and QHCl-best at the higher concentration levels. 6. Breadth of responsiveness was measured using the equation developed by Smith and Travers. At the concentrations used to examine hamster chorda tympani fibers, IXth nerve fibers were not very responsive and were quite narrowly tuned to the four taste qualities. At higher concentrations the fibers became more broadly responsive across the four stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)     

Human Type II Taste Cells Express Angiotensin-Converting Enzyme 2 and Are Infected by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)

Chemosensory changes are well-reported symptoms of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The virus targets cells for entry by binding of its spike protein to cell-surface angiotensin-converting enzyme 2 (ACE2). It is not known whether ACE2 is expressed on taste receptor cells (TRCs), or whether TRCs are infected directly. in situ hybridization probe and an antibody specific to ACE2 indicated presence of ACE2 on a subpopulation of TRCs (namely, type II cells in taste buds in taste papillae). Fungiform papillae of a SARS-CoV-2⁺ patient exhibiting symptoms of coronavirus disease 2019 (COVID-19), including taste changes, were biopsied. Presence of replicating SARS-CoV-2 in type II cells was verified by in situ hybridization. Therefore, taste type II cells provide a potential portal for viral entry that predicts vulnerabilities to SARS-CoV-2 in the oral cavity. The continuity and cell turnover of a patient''s fungiform papillae taste stem cell layer were disrupted during infection and had not completely recovered 6 weeks after symptom onset. Another patient experiencing post–COVID-19 taste disturbances also had disrupted stem cells. These results demonstrate the possibility that novel and sudden taste changes, frequently reported in COVID-19, may be the result of direct infection of taste papillae by SARS-CoV-2. This may result in impaired taste receptor stem cell activity and suggest that further work is needed to understand the acute and postacute dynamics of viral kinetics in the human taste bud.     

Long-term effects of nicotine on rat fungiform taste buds

Nicotine, an alkaloid found in tobacco smoke, has been recognized as capable of inducing changes in taste functionality in conditions of chronic exposure. The mechanisms underlying these sensory alterations, however, are currently unknown. We addressed this issue by studying the long-term effects of nicotine on the anatomical features of taste buds, the peripheral end-organs of taste, in rat fungiform papillae. Nicotine was administered to rats via drinking water over a period of 3 weeks, which represents a standard method to achieve chronic drug exposure in laboratory animals. We found that prolonged administration of nicotine induced a significant reduction in the size of fungiform taste buds, without affecting their total number on the rat tongue. Morphometric measurements as well as evaluations of taste cell membrane capacitance suggested that the reduced size of taste organs was determined by a decrease in the number of cells per taste bud. In addition, chronic treatment with nicotine caused an increase in the relative density of cells expressing gustducin, a specific G protein alpha-subunit found in some taste cells and involved in bitter/sweet transduction. Interestingly, changes in the expression pattern of gustducin turned out to be more pronounced in periadolescent/adolescent than in adult rats. As a whole, our data indicate that long-term nicotine administration induces significant changes in the anatomical properties of taste buds in rat fungiform papillae. These changes could have a profound impact on the sensory information relayed to the brain; therefore, they may be responsible, at least in part, for the alterations in taste functionality observed during chronic nicotine exposure, a condition found in regular smokers.     

Maturation of taste buds on the soft palate of the postnatal rat

Taste bud distribution on the soft palate and within three types of tongue papillae (fungiform, foliate, and circumvallate) were examined histologically in the rat at different postnatal ages. After paraffin embedding, serial sections (10 microm) were made and stained by HE, and digitized images of each section were examined. The existence of a taste pore was used to identify mature taste buds. At birth, 53% (68 of 127 observed) of the taste buds on the soft palate, but only 14% (14 of 110 observed) within fungiform papillae, contained a taste pore. One week after birth, the number of mature taste buds increased rapidly, resulting in 90% of soft palate taste buds and 80% of fungiform taste buds containing taste pores. In contrast, no taste buds with pores were observed at birth within foliate and circumvallate papillae; however, at two weeks after birth 52% (71 of 132 observed) of the foliate and 68% (180 of 267 observed) of the circumvallate taste buds examined contained taste pores. These results suggest that taste buds within the soft palate play an important role in the detection of nutrients in the neonatal rat.     

Morphological characteristics of the tongue and its papillae in the donkey (Equus asinus): a light and scanning electron microscopical study

The morphology of the donkey tongue and its papillae were investigated by macroscopy and by light and scanning electron microscopy in ten adult animals (six males and four females). The spatula-shaped tongues measured about 28 cm in length, 4.5 cm in breadth and 3.5 cm in thickness. Samples from different areas of four tongues were grossly examined and pieces were processed for light and scanning electron microscopy. Filiform papillae were distributed mainly on the dorsum of the tongue, being thin and relatively short at the apex, conical and scaly in the main part (triangular zone) of the body, and thin and longer at the caudal part of the body. Few of them were found on the lateral surfaces. Fungiform papillae appeared scattered mainly on the lateral surfaces. They were mostly rounded (about 1.0 mm in diameter), but lobulated forms were also observed. Filiform and fungiform papillae were both completely devoid of taste buds, indicating a more mechanical function. The vallate papillae were 2-3 in number, located at the most caudal part of the body. They were three to four times as large as the fungiform papillae (about 5.6 mm in diameter) each with a wide circular groove around the central bulbous projection. Secondary grooves originating from the primary one were also demonstrated. The vallate papillae contained many taste buds with taste pores opening deeply into the papillary groove. Fine filiform papillae were demonstrated on the bulb-like part of the vallate papillae. The donkey tongue had sinister and dexter well-developed sets of foliate papillae close to the basis of the palatoglossal arch. They were arranged in the form of numerous leaves separated by deep, variably wide grooves and contained a very large number of taste buds. It is believed that the existence of well developed foliate papillae in donkey may substitute the comparatively few vallate papillae in this species.     

Differentiation of alpha-gustducin in taste buds of the mouse soft palate and fungiform papillae

We used alpha-gustducin, a type II taste-cell-specific G protein, to investigate the onset of taste transduction and its relation to the development of the soft palate (SP) and fungiform (FF) papillae taste buds in the mouse. Paraffin wax embedded sections were prepared from the SP and anterior region of the tongue of the mouse from birth until postnatal day (PD) 63. No alpha-gustducin-immunoreactive cells were observed on the day of birth. One day later, alpha-gustducin was immunolocalised in taste buds with pores with a relatively higher frequency recorded in the SP as compared with the FF papillae. The immunoreactive cells were spindle shaped with elongated processes extending from the base to the pore of the taste buds. On PD 7, the number of taste buds containing alpha-gustducin-immunoreactive cells in the SP was three times greater than that of FF papillae. Our results indicate that taste transduction is essentially acquired from the time of birth. Moreover, the onset of taste transduction by the SP taste buds developed earlier than that achieved by taste buds in the FF papillae.     

Light and scanning electron microscopic study on the lingual papillae and their connective tissue cores of the Cape hyrax Procavia capensis

We examined the epithelial surface and connective tissue cores (CTCs) of each lingual papilla on the Paenungulata, Cape hyrax (Procavia capensis), by scanning electron microscopy and light microscopy. The tongue consisted of a lingual apex, lingual body and lingual root. Filiform, fungiform and foliate papillae were observed on the dorsal surface of the tongue; however, fungiform papillae were quite diminished on the lingual prominence. Moreover, no clearly distinguishable vallate papillae were found on the tongue. Instead of vallate papillae, numerous dome-like large fungiform papillae were arranged in a row just in front of the rather large foliate papillae. Foliate papillae were situated in the one-third postero-lateral margin of the lingual body. The epithelium of filiform papillae was covered by a keratinized layer with kerato-hyaline granules, whereas weak keratinization was observed on the interpapillary epithelium. The external surface of the filiform papillae was conical in shape. CTCs of the filiform papillae were seen as a hood-like core with a semicircular concavity in the anterior portion of each core. Large filiform papillae were distributed on the lingual prominence. The CTCs of large filiform papillae after exfoliation of their epithelium consisted of a concave primary core and were associated with several small protrusions. The surface of fungiform papillae was smooth and dome-like. After removal of the epithelium, CTCs appeared as a flower bud-like primary core and were associated with several protrusions that were arranged on the rim of the primary core. Several taste buds were found on the top of the dorsal part of the epithelium of both fungiform and large fungiform papillae. Well-developed foliate papillae were seen and numerous taste buds could be observed in the lateral wall of the epithelium in a slit-like groove. The morphological characteristics of the tongue of the Cape hyrax had similarities with other Paenungulata such as Sirenia. However, three-dimensional characteristics, especially CTCs of lingual papillae, exhibited multiple similarities with rodents, insectivores and artiodactyls.