Morphological Study of the Persian Leopard (Panthera pardus saxicolor) Tongue

This study described the morphological features of the Persian leopard (Panthera pardus saxicolor) tongue using light and scanning electron microscopy techniques. The keratinized filiform papillae were distributed all over the entire dorsal surface of the tongue and contained small processes. They were changed into a cylindrical shape in the body and conical shape in the root. The fungiform papillae were found on the apex and margin of the tongue. Few taste pores were observed on the dorsal surface of each papilla. The foliate papillae on the margins of the tongue were composed of several laminae and epithelial fissures. Taste buds were not seen within the non‐keratinized epithelium. The vallate papillae were six in total and arranged in a “V” shape just rostral to the root. Each papilla was surrounded by a groove and pad. Taste buds were seen within their lateral walls. Lyssa was visible on the ventral surface of the tongue tip and was found as cartilaginous tissue surrounded by thin connective tissue fibres. The core of the tongue was composed of lingual glands, skeletal muscle and connective tissue. These glands were confined to the posterior portion of the tongue and were composed of many serous cells and a few mucous cells. The results of this study contributed to the knowledge of the morphological characteristics of the tongue of wild mammals and provided data for the comparison with other mammals.     

Characteristics of Filiform, Fungiform and Vallate Papillae and Surface of Interface Epithelium-Connective Tissue of the Maned Sloth Tongue Mucosa (Bradypus torquatus, Iliger, 1811): Light and Scanning Electron Microscopy Study

The study of lingual surfaces and the surface of interface epithelium-connective tissue of the tongue of Bradypus torquatus was performed by employing the light and scanning electron microscopy (SEM) techniques. The results revealed that the rostral part of the tongue presents a round apex and covered by filiform and fungiform lingual papillae and a ventral smooth surface. It was observed that the epithelial layer of the dorsal surface possesses the basal, spinosum, granular and cornified epithelial cells. The lamina propria is characterized by a dense connective tissue forming the long, short and round papillae. Numerous typical filiform papillae are located especially in the rostral part intermingled for few fungiform papillae, which were revealed in three-dimensional SEM images. Usually, the fungiform papillae are located in the border of rostral apex of the tongue exhibiting the rounded form. They are covered by keratinized epithelial cells. In the fungiform papillae, several taste pores were observed on the surface. The vallate papillae presented numerous taste buds in the wall of epithelial cells, being that the major number of taste buds is located on the superior half of vallate papilla. The taste pores are surrounded by several laminae of keratinized epithelial cells. The samples treated with NaOH solution and examined by SEM revealed, after removal of the epithelial layer, the dense connective core in original disposition, presenting different sizes and shapes. The specimens stained with Picrosirius and examined by polarized light microscopy revealed the connective tissue, indicating the collagen fibres type I and type III.     

Anatomical and surface ultrastructural investigation of the tongue in the straw-coloured fruit bat (Eidolon helvum,Kerr 1972)

The morphology of tongue in straw-coloured fruit bat from tropical forests was evaluated in relation to frugivorous diets and in comparison with other species that consumes other food types. Gross, stereomicroscopy, scanning electron microscope and histological methods were used. The tongue was relatively long with round tip, which closely fitted into oral cavity. Five types of mechanical papillae included crown-like and trifid filiform papillae. Also bulky, cone-shaped papillae and long conical papillae were identified. These mechanical types also showed variations in shape, size and number of processes of papillae. Transitional forms of these mechanical papillae were present. Fungiform papillae with taste pores were interposed amongst filiform types in apex and body; three ovoid-shaped vallate papillae were in triangular arrangement on root and displayed taste pores. Some bulky, cone-shaped papillae surrounded the vallate papillae. Histologically, mechanical filiform types showed highly keratinized stratified squamous epithelium and dense connective tissue core with secondary papillae. Taste buds appeared in fungiform and vallate papillae. Neutral and acidic secretions were identified in lingual glands of root. The presence of prominent filamentous processes of filiform papillae and conical papillae of the tongue in conjunction with gustatory papillae ensures adaptation to copious fruit diets. The gross morphometric and histometric parameters of the tongue did not differ remarkably from previous values obtained for some fruit bats with comparable weight. This investigation showed similarities with fruit bats such as large flying fox and Egyptian fruit bat and reflect common diet and feeding habits but varied from insectivorous and nectivorous bats.     

Absence of hyaline cartilage in the tongue of 'Caspian miniature horse'

Histology of the tongue, including apex, root and body, in four adult Caspian miniature horses was examined. Serial sections with 6 mum thickness were stained with haematoxylin-eosin and Masson trichrome and studied under light microscope. The tongue was covered by stratified squamous epithelium. It was thick and keratinized bearing numerous lingual papillae on the dorsum, mostly filiform with a very fine keratinized thread projecting above the surface and bending backward. The fungiform papillae were sparsely scattered among the filiform papillae and covered with keratinized squamous epithelium. Few taste buds were detected on it. The two very large vallate papillae were detected on the dorsum, just rostral to the root, which were covered with stratified squamous epithelium with relatively high amounts of taste buds in the epithelium of the surrounding grooves. The foliate papillae were present near the palatoglossal arch and had a few taste buds. The epithelium covering the ventral surface of the tongue was thin and keratinized. The lingual muscle core consisted of transverse, longitudinal and perpendicular bundles of skeletal muscle fibres. Clusters of minor salivary glands were present between the muscle fibres and lamia propria. Most of the lingual glands were mucous and most of the gustatory ones were serous type. The mid-dorsal special structure of the tongue (dorsal lingual cartilage) contained sparse skeletal muscle fibres and was rich in white adipose tissue. Hyaline cartilage, routinely observed in this structure in the horses, was not detected in Caspian miniature horse.     

Characteristics of Dorsal Lingual Papillae of the Bactrian Camel (Camelus bactrianus)

The morphology of dorsal lingual papillae of the Bactrian camel (Camelus bactrianus) was studied by using light and scanning electron microscopy. Filiform and lenticular papillae were considered as mechanical papillae but fungiform and vallate papillae were considered as gustatory papillae. Filiform papillae were distributed mostly in the anterior two-thirds region of the tongue. Each filiform papilla consisted of one primary papilla and a few smaller secondary papillae. Lenticular papillae were distributed on the torus linguae. The larger papillae were arranged in two parallel lines medially whereas the smaller papillae were laterally located. Most of the fungiform papillae were found on the lateral margins of the anterior two-thirds of the tongue. These papillae were small and round. Intra-epithelial taste buds were located on the dorsal surface of each papilla. The vallate papillae were arranged in two rows on each rim of the torus linguae. Each round- and flat-shaped vallate papilla was surrounded by a prominent gustatory groove and an annular pad. A few taste buds were observed in the lateral epithelium of the papillae. The keratinization of the covering stratified squamous epithelium of the mechanical lingual papillae was relatively thicker than those of the gustatory papillae. The lingual papillae of the Bactrian camel exhibited some different characteristics from other domestic ruminants. These morphological characteristics of the tongue of the Bactrian camel might have evolved to assist the camel in prehension and manipulating of the inorganic stiff plants that grow in its environment and therefore might relate to the feed and feeding habits of the animal.     

Scanning Electron Microscopic Study of the Lingual Papillae in the Arctic Fox (Alopex lagopus L., 1758)

This study aims to show the distribution and the three-dimensional structure of the lingual papillae in the arctic fox. The macro- and microscopic structure of the tongue and its lingual papillae was studied in 11 adult arctic foxes. Two types of mechanical papillae were distinguished on the dorsal surface of the tongue – filiform papillae and conical papillae. The gustatory papillae in the arctic fox are represented by fungiform, vallate and foliate papillae. The keratinized filiform papillae on the anterior part of tongue are composed of one big posterior process accompanied by 10–12 secondary anterior processes. The number of anterior processes of filiform papillae undergo a complete reduction within the area between the posterior part of the body of the tongue and area of the vallate papillae. The conical papillae cover the whole dorsal surface of the root of the tongue, including the lateral parts surrounding the area of the vallate papillae and the posterior part of the root. The size of the conical papillae increases towards the root of the tongue but their density decreases. In the arctic fox, there are three pairs of vallate papillae distributed on the plan of a triangle. The diameter of vallate papillae in each successive pair is bigger. The wall surrounding the body of the vallate papilla and its gustatory trench is composed of six to eight conical papillae joined at various degree. The foliate papillae on both margins of the tongue consist of seven to nine laminae.     

Morphological Characteristics of the Vallate Papillae of the One‐Humped Camel (Camelus dromedarius)

In this study, the morphology of the vallate papillae of camel was investigated using gross, light and scanning electron microscopy as well as immunohistochemistry. Vallate papillae were arranged along an identical line on each side of the lingual torus and revealed remarkable individual differences. However, each papilla – round or flat, small or large, single or paired – was surrounded by a prominent groove and an annular pad. Based on our findings, postnatal development and formation of new papillae occur in camel. Microscopically, taste buds were constantly observed along the medial wall epithelium, and in the papillary wall epithelium on both sides of the secondary groove apparently separating the vallate papillae. In addition, an aggregation of taste buds was occasionally observed at the bottom of the lateral wall epithelium. Using SEM, we observed several pits and microplicae on the surface of papillae as well as distinct taste pores on the peripheral parts of the dorsal surface. We demonstrated immunoreactivity of α‐gustducin only in mature taste buds. We conclude that the morphological features and microstructure of vallate papillae are a characteristic feature in camel compared to other ruminants. These features might have evolved to assist the camel in the manipulation and tasting of thin organic stiff plants that grow in its environment and therefore might have related to the feeding habits of the animal.     

Fungiform papillae of the tongue in the rabbit (Oryctolagus cuniculus)

Examinations were conducted on four tongues of adult rabbits (Oryctolagus cuniculus). On the basis of observations in a scanning electron microscope (SEM) it was found that fungiform papillae in the rabbit are located on the dorsal surface of the apex and body of the tongue, in the front of the torus of the tongue and on the margins of the tongue. Moreover, fungiform papillae are located laterally in relation to the torus of the tongue and are arranged linearly. Fungiform papillae are distributed among filiform papillae and are separated from them by the interpapillary epithelium. The connective tissue core of fungiform papillae is formed from the body, narrow at the base and wider at the apex and 10-17 crest-like folds arranged around them. On the dorsal surface of the connective tissue core of fungiform papillae there are impressions of taste buds and occasionally traces of lymphatic nodules.     

Tongue Papillae in Goat: a Scanning Electron-Microscopic Study

The tongue papillae of 6-9-month-old Jamunapari goats were studied by scanning electron-microscopy. The conical-shaped filiform papillae had 3–6 pointed projections and 6–8 secondary papillae at the free tip and the base of the dorsal surface of the tongue, respectively. The convex surfaced fungiform papillae were raised above the lingual mucosa. The vallate papilla was characterized by a papillary groove and an annular pad. The large conical papilla had a round base and a blunt tip without any projection. Two types of lenticular papillae could be distinguished. The irregular surface of all types of papillae revealed microplicae in the form of microridges and micropits. The fungiform papilla was studded with microvilli. The taste pores were oriented on the dorso-lateral surface of the vallate papilla.     

scanning electron microscopy of lingual papillae in the common shrew, Sorex araneus, L

The dorsal surface of the tongue of the adult common shrew (Sorex araneus L.) was examined by scanning electron microscopy. As in the other insectivores, three types of lingual papillae were observed: filiform, fungiform and vallate papillae. The filiform papillae represented the most numerous type of lingual papillae. The characteristic feature of the filiform papillae, covering the apex and corpus of the tongue, is the two processes tilted to the root of the tongue. The filiform papillae on the lingual apex are reduced in size and structure. Five to six fungiform papillae are placed symmetrically along the left and right border of the corpus of the tongue. Two large oval vallate papillae are located on the radix of the tongue. The posterior surface of the tongue in common shrew is covered with a smooth mucosa with the openings of the serous glands.     

Anatomical and scanning electron microscopic study of the tongue in the African giant pouched rats (Cricetomys gambianus,Waterhouse)

The African giant pouched rat is a nocturnal, fossorial and omnivorous wild rodent widely distributed in sub‐Saharan Africa. The morphology of lingual surface has not previously examined and was investigated by gross dissection, stereomicroscopy, scanning electron and light microscopy. Grossly, it was elongated and dorso‐ventrally flattened with rounded tip. It measured 3.48 ± 0.33 cm in length, with a median groove of 1.4 ± 0.1 cm in length and well‐developed lingual prominence. Stereomicroscopically, filiform, fungiform and vallate papillae were indicated in the apex, body and root. Fungiform papillae intermingled with filiform on the ventral and dorsal surface of the apex and body. Three vallate papillae were located in triangular arrangement on the root. The surface ultrastructural features distinguished four types of filiform which varied in size, shape and distribution: first type with long pointed process was preponderant on the apex and body of tongue; the second with robust base was located on central lingual prominence; the third (caudal body) was conically shaped with pointed process; and the fourth type (root) had forked filamentous process. Large oval‐shaped fungiform papillae were apparent. Each vallate was surrounded by a circumferential groove into which taste pores opened. Histologically, the tongue surface displayed moderately keratinized stratified squamous epithelium, and lamina propria that varied in places. Fungiform and vallate showed spindle‐shaped taste buds. Serous and mucous acini containing neutral and acidic mucins were observed in lamina propria of root. The structural adaptations of the tongue to omnivorous diet and food manipulation in oral cavity were comparatively discussed.     

Anatomical and histological structure of the tongue and histochemical characteristics of the lingual salivary glands in the Chukar partridge (Alectoris chukar,Gray 1830)

1. The aim of the study was to examine the morphology of the tongue and the histochemical features of the lingual salivary glands in this species.

2. The tongue was elongated, terminating in a rather sharp, dagger-like apex. On the surface of the tongue and situated between the body and root of the tongue, two rows of conical papillae, the sharp apices of which pointed towards the posterior part of the tongue, were observed. The keratinised epithelium lining the dorsal surface lacked typical gustatory papillae. However, it was observed that taste buds were present in the epithelium of the lingual body and root. The tongue was supported by a structure composed of hyaline cartilage, the paraglossum, which extended from the lingual root to the apex. Simple branched tubular glands, which were encapsulated by connective tissue, were embedded within the submucosa in the body (anterior salivary glands) and root (posterior salivary glands) of the tongue. It was observed that the secretion of the lingual glands contained neutral mucins, proteoglycans containing carboxylic acid, weak and strong sulphated groups, N-acetylated sialomucins, but lacked glycogen.

3. It was demonstrated that, the general morphological features, papillary distribution of the tongue and the histological structure of the mucosa epithelium and the supportive elements displayed similarity to those of other domestic avian species. It was also determined that, in view of the particular feeding types, in the partridge, the presence of the papillary crest was not correlated with diet.     

Morphology of the dorsal lingual papillae in the black rhinoceros (Diceros bicornis)

The dorsal lingual surface of a black rhinoceros (Diceros bicornis) was examined by scanning electron microscopy. The tongue was about 30 cm in length. There were about 60 vallate papillae on both sides. Filiform, fungiform and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue. The papillae had a hair-like shape. The fungiform papillae were round in shape, and more densely distributed on the lingual apex. No foliate papillae were seen on the dorsal surface. The vallate papillae were located on both sides of the posterior end of the lingual body. Each papilla was surrounded by a groove.     

Scanning electron microscopy study of the lingual papillae in the European mole (Talpa europea, L., Talpidae)

The tongue in the adult European mole (Talpa europea L.) was examined by scanning electron microscope. The elongated tongue with a rounded apex is about 12-13 mm in length and 3-4 mm in width. On the apex the shallow median groove is present. On the dorsal surface of the lingual mucosa two types of mechanical papillae and two types of gustatory papillae were observed. Mechanical papillae are represented by numerous filiform papillae with a single process, covering the whole surface of the apex and body of the tongue, and massive conical papillae, found on the root of the tongue. The structure and density of filiform papillae varies in the anterior and posterior part of the tongue. A unique trait of the tongue in the European mole is the occurrence on the apex of the tongue of a single row of conical papillae. Gustatory papillae are represented by numerous fungiform papillae and one pair of vallate papillae. Dome-shaped fungiform papillae in the anterior part of the tongue are arranged linearly along both margins of the tongue, whereas in the posterior part of the body of the tongue flat fungiform papillae are distributed evenly among filiform papillae. Oval vallate papillae are surrounded by a continuous furrow and a single pad. In the posterior part of the root behind conical papillae the surface of the mucosa is flat with numerous orifices of lingual papillae located there. Observations on the distribution and structure of gustatory papillae in the common mole did not show the existence of special traits, differing them from those in terrestrial insectivores. The comparison of the morphology of the tongue, the distribution and structure of the lingual papillae in the European mole with those in the other species of Insectivores, indicated of a general similarity of features within the family Talpidae.     

Morphological study of the lingual papillae in the barking deer, Muntiacus muntjak

The morphology of the tongue of the adult barking deer, Muntiacus muntjak, was examined by light and scanning electron microscopy. The result showed that the tongue of the barking deer was elongated with a rounded apex. Four types of lingual papillae were observed: filiform, fungiform, vallate and large conical papillae. The filiform papillae represented the most numerous types of lingual papillae. The fungiform papillae were distributed among the filiform papillae on the rostral and the body portions of the tongue. Ten to thirteen vallate papillae were distributed on both sides of the lingual prominence among the large conical papillae. Histologically, both the fungiform and vallate papillae contain taste buds in the epithelial layer. The distribution and types of lingual papillae found in the barking deer are similar to those in the other species that belong to the family Cervidae.     

Distribution of the lingual lymphoid tissue in domestic ruminants

The distribution and organisation of the intralingual lymphoid tissue was studied in sheep, goat and cattle. For each species, the tongues of two animals were harvested and divided in sample blocks extending over the total surface of the tongue. With 2.5 mm intervals, ten serial histological sections were made for conventional histological staining (haematoxylin-eosin, Van Gieson, Masson's trichrome) and immunohistochemical staining of lymphoid cells (anti-CD3, anti-CD21, anti-CD45). Lymphocytes were scattered in the subepithelial propria-submucosa and in the connective tissue cores of the lingual papillae. The connective tissue cores of fungiform papillae, including those located on the lingual apex, and vallate papillae showed relatively more lymphocytes than the propria-submucosa. Lymphoid cell aggregations were even more abundant beneath the grooves surrounding the vallate papillae in small ruminants. In cattle, a well-organised lingual tonsil was additionally found at the root of the tongue. CD3-positive lymphocytes were observed in all species examined. CD21-positive lymphocytes were numerous in the lymphoid nodules of the bovine lingual tonsil but very scarce in the ovine and caprine tongues. Therefore, the lymphoid cell aggregations in the tongues of small ruminants should not be referred to by the term 'lingual tonsil'.     

Gross and microscopic observations on the lingual structure of the Florida Manatee Trichechus manatus latirostris

The tongue of the Florida manatee (Trichechus manatus latirostris) was studied macroscopically, light and electron microscopically. The tongue was slender, muscular and firmly fixed in the oral cavity; only the cranial tip was free and mobile. Numerous filiform papillae were distributed over the dorsal surface of the rostral tongue. Multiple raised, round fungiform-like papillae were distributed over most of the dorsum. Typical fungiform papillae were restricted to the lateral margins of the tongue. Foliate papillae, presenting as multi-fossulate openings, were noted on the caudolateral margins. Open pits were located on the dorsocaudal surface and lateral walls. Microscopic examination showed that most of the lingual dorsum was covered with a thick stratified squamous epithelium. Open pits led to well-developed mucous salivary glands. Glands within the foliate papillae were mostly mucous, although some seromucous glands were present. Taste buds were restricted to the epithelium of the foliate papillae. Throughout the tongue, striated muscle was abundant below the epithelium. Blood vessels, lymph channels and nerve fibres were freely distributed throughout the intermuscular stroma. Nerve fibres reacted positively with neurone specific enolase (NSE) antibody throughout the tongue, including nerve bundles, glands and taste buds. Clear to translucent vacuoles were found juxtaposed to nuclei in the stratum spinosum in the foliate papillae epithelium.     

Morphogenesis of lingual papillae of one‐humped camel (Camelus dromedarius) during prenatal life: A light and scanning electron microscopic study

This study was made on 24 camel fetuses of crown‐rump vertebral length (CVRL) ranging from 10.5 cm to 105 cm CVRL (94–352 days old). These camel fetuses were classified into three groups representing the three trimesters of prenatal life. During the first trimester (94–142 days), lingual papillae (circumvallate and lentiform papillae) were demonstrated on the lingual root, but lingual body and the apex were almost free of papillae except for some scattered epithelial projections especially near the lateral borders of the body. In the second trimester (152–229 days), the lentiform papillae covered the entire root of the tongue except for areas occupied by the circumvallate papillae. Taste buds with clear pores were observed for the first time in areas between the circumvallate gustatory furrow and surface epithelium of the tongue. In addition, short numerous filiform papillae were observed on the rostral part of the lingual body and the lateral parts of the apex. Fungiform papillae, however, were demonstrated amidst the filiform papillae. In this trimester, taste buds were also seen on the top of the fungiform papillae. In the third trimester (256–352 days), all lingual papillae were clearly demonstrated on the dorsum of the root, body and apex of the tongue. Both types of gustatory papillae (circumvallate and fungiform) had well‐developed taste buds. Mechanical papillae (filiform and lentiform) were well developed. Lentiform papillae occupied most of the dorsal aspect of the Torus linguae; they were larger in size with semicircular apices. Filiform papillae, however, were numerous and demonstrated heavily on the lateral and rostral parts of the body as well as on the apex of the tongue.     

Morphology of the dorsal lingual papillae in the Japanese macaque and Savanna monkey

The dorsal lingual surfaces of infant Japanese macaque (Macaca fuscata) and adult savanna monkey (Cercopithecus aethiopus) were examined by scanning electron microscopy. Filiform, fungiform, foliate and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue. The fungiform papillae were round in shape, and more densely distributed on the lingual apex. The foliate papillae were seen on the dorsolateral aspect of the tongue. The three vallate papillae were arranged like a triangle with the apex of the triangle directing caudally. Each papilla was surrounded by a groove. The rudiments of the fungiform, foliate and vallate papillae were visible earlier than those of the filiform papillae.