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.     

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.     

Morphological and scanning electron microscopic studies of the tongue of the Egyptian fruit bat (Rousettus aegyptiacus) and their lingual adaptation for its feeding habits

This study was carried out on the tongues of 12 adult normal healthy Egyptian fruit bats of both sexes. The tongue is protrusible, elongated flat with a rounded apex and its wide and thickness increase gradually toward the lingual root. There are four types of lingual papillae; two mechanical and two gustatory. The tongue divided into three parts (anterior, middle and posterior), each part subdivides into three regions; two lateral regions and median region, in addition to the lingual apex to the anterior region. The lingual papillae close to the median region of the tongue were posteriorly directed toward the pharynx, while theses present on the lateral regions of the tongue are directed medioposteriorly. There are sex subtypes of the filiform papillae; three on the anterior part (small, conical and giant), two on the middle part (cornflower and leaf-like papillae) while the posterior part contain rosette shape filiform papillae, in addition to transitional papillae and conical papillae. Two gustatory papillae represented by; small number of fungiform papillae which scattered among the filiform papillae on lingual apex and two lateral regions of the anterior and middle part of tongue, while the three circumvallate papillae on the posterior part were arranged in a triangle form.     

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.     

Morphological study of the lingual papillae in the fruit bat (Rousettus amplexicaudatus) by scanning electron microscopy and light microscopy

This study was carried on the tongues of ten normal, healthy and adult fruit bats (Rousettus amplexicaudatus, also known as the nyap biasa bat) in Yogyakarta, Java Island, Indonesia. The tongue was protrusible, elongated and flat with a rounded apex, and its width and thickness increased gradually towards to lingual root. There were two main types of lingual papillae, mechanical (filiform) and gustatory (fungiform and circumvallate). The tongue was divided into three parts (apex, corpus and radix), and then, each part was subdivided into three regions (two lateral regions and a median region). There were six subtypes of the filiform papillae—three types on the anterior part (small, scale-like and giant), one type on the middle part (leaf-like papillae) and two types on the posterior part (rosette-shaped filiform and conical filiform papillae)—in addition to transitional papillae presented on the corpus and radix. Two types of gustatory papillae were represented by a small number of fungiform papillae that are scattered among the filiform papillae on the lingual apex and corpus, while three circumvallate papillae on the posterior part are arranged in a “V” shape pointing directly at the larynx.     

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.     

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.     

Papillary architecture of the Leopardus pardalis tongue

The ocelot (Leopardus pardalis) is a Felidae of wide geographical distribution and food flexibility; therefore, it is essential to understand the morphology of the species. Thus, we aimed to describe its lingual morphology in order to gain information regarding the anatomy of this carnivore's digestive system. The tongues ??were removed for ex situ macroscopic and morphometric analyses, as well as for light microscopy and scanning electron microscopy, of fragments of the different lingual regions. The tongue of L. pardalis had an elongated form that was subdivided into the apex, body and root, in which four papillary types were observed: filiform, fungiform, circumvallate and conical. It presented with a stratified, keratinized squamous epithelium, followed by loose and dense connective tissues, as well as a skeletal striated musculature that comprised most of the organ. In addition, in scanning electron microscopy the filiform papillae showed a complex with multiple layers of keratin with triangular shape projected caudally in oral cavity. The fungiform papillae were distributed among the filiform and showed a rounded shape with some gustatory pores, and are keratinized but in a lower intensity if compared with filiform. The vallate papillae, located in lingual root, showed an oval format, had a deep groove surrounded the papillae and some gustatory pores. The conical papillae are located in lingual root and are similar to the filiform. The tongue of L. pardalis resembles other carnivorous species, mainly among felids. However, it differed in relation to the quantity of vallate papillae and the absence of foliate papillae.     

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.     

Morphological characterization of Horsfield’s treeshrew Tupaia javanica lingual papillae: Light microscopy and scanning electron microscopy studies

The Horsfield's treeshrew (Tupaia javanica) is one of the shrews found on the island of Java that mainly feeds on fruits and occasionally insects. This shrew has an important role in the ecosystem as it spreads plant seeds and controls insects. To this day, there is no available knowledge about the structure of Horsfield's treeshrew's tongue. Therefore, the aim of this study was to provide data on the tongue structure of the Horsfield's treeshrew through two different methods. We investigated the tongue morphology and lingual papillae distribution of Tupaia javanica using 1) scanning electron microscopy (SEM) for microscopic structure and 2) histology for microscopic organization. Our macroscopic results revealed that the tongue of Tupaia javanica can be divided into three parts: apex, corpus and radix. The dorsal surface of the medial corpus is the median groove extending to the radix. Observation using SEM and light microscopy (LM) showed that the apex of the tongue bears three types of papillae: scale-like filiform, small filiform and fungiform. These are rosette filiform papillae, cornflower filiform papillae, conical papillae and fungiform papillae in the corpus. Meanwhile, the radix contains small filiform papillae, scale-like filiform papillae, vallate papillae, conical papillae and fungiform papillae. On the lateral posterior radix, Weber's gland reacts positively to PAS reaction. Taking together, our research shows that there are variations in the papillae on the tongue surface of Horsfield's treeshrew, and the variations of these papillae are very dependent on the pattern, type of food and the function of the tongue.     

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.     

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.     

Ultrastructure of Lingual Papillae in Common Chimpanzee (Pan troglodytes) Foetus,Newborn and Adult Specimens

Among primates, the two recognized species of chimpanzees (common chimpanzee, Pan troglodytes; pygmy chimpanzee, Pan paniscus) are considered to be the most similar to humans. Importantly, in mammals, the food intake behaviour largely determines the tongue morphology, including the type, proportion and distribution of gustatory and non‐gustatory tongue papillae. The lingual papillae form during its development and mature in post‐natal life depending on the different feeding. In this study, we have used scanning electron microscopy to analyse the age‐related changes in the lingual papillae of foetal, newborn and adult P. troglodytes. Four main types of lingual papillae, denominated filiform, fungiform, foliate and vallate, and one subtype of filiform papillae called conical papillae, were found. The main age‐related changes observed in all kinds of papillae were a progressive keratinization and morphological complexity along the lifespan. During the foetal period, there was scarce keratinization, which progressively increases in young animals to adulthood. The number of filiform increased with ageing, and both filiform and fungiform papillae in adult tongues are divided into pseudopapillae. On the other hand, the vallate papillae vary from smooth simple surfaces in foetal tongues to irregular surfaces with grooves and pseudopapillae (microscopic papilla‐shaped formations within the papilla itself) in adults. These results describe for the first time the age‐related variations in the three‐dimensional aspect of lingual papillae of the chimpanzee tongue and provide new data to characterize more precisely these structures in the human closest specie.     

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.     

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.     

Morphological Studies of the Tongue of the Egyptian Water Buffalo (Bubalus bubalis) and Their Lingual Papillae Adaptation for Its Feeding Habits

This work was conducted to describe the morphological characters of the tongue of Egyptian water buffalo (Bubalus bubalis). The lingual root and the dorsal middle region of apex and body in addition to the dorsal and ventral surface of lingual tip were devoided from any fungiform papillae. The lingual tip contains conical papillae only. The ventral surface of lingual apex was divided into two portions by the U‐shaped fungiform line into papillary and non‐papillary region. Histological investigation on the lingual surface epithelium and lamina propria submucosa reflects differences in these layers in different parts of the tongue. By SEM, there are two subtypes of filiform papillae: caudally directed papillae on dorsal surface and rostrally directed papillae on the lateral region of ventral surface of lingual apex. There are two subtypes of conical papillae: small slightly rostrally directed papillae on dorsal and ventral surface of lingual tip and large posteromedially directed papillae on dorsal surface of lingual root. The rounded circumvallate papillae consisted of round bulb surrounded by deep circular groove, which surrounded by circular pad. Higher magnification of filiform papillae indicates the presence of microcrests separated by microgrooves, and these microgrooves consisted of microrodes. The fungiform surface having micropores on the tip of elevated tubercle for taste buds pores. All these observed structures (microcrests, microgrooves, microrodes, tubercles, microridges) in a higher magnification allow animals to transport food particles through the oral cavity and help in the defensive behaviour. There are strong correlations between the tongue anatomical characteristics and its functions.