Scanning electron microscopy of the tongue papillae in the pig (Sus scrofa)

A clear understanding of the role of different papillae in the pig may permit the development of a more palatable diet, thus, better utilizing anatomical structures and morphological characteristics to enhance health and productivity in this domestic species. The study used ten healthy market-size, mixed-breed pigs to properly describe the surface structure of the tongue papillae using standard scanning electron microscopic techniques. Two types of sharp and blunt filiform papillae were identified. Fungiform papillae, located on the lateral side of the tongue, were circular and large with surface taste pores. The majority of oval papillae on the dorsal surface of the tongue contained multidirectional surface grooves and lacked taste pores. The foliate papillae, located principally on the caudal third and lateral part of the tongue, were comprised of four to five leaves and they had additional pseudopapillae. The two vallate papillae, found in the caudal third and dorsum of the tongue, had a well-defined vallum and pseudopapillae on their surface. At the root of the tongue, two types of conical papillae with or without apex were observed. The entire area covered by conical papillae was deeply occupied by lingual tonsils. The lingual tonsils were scattered with varying sized lymph nodules in the propria mucosa of the conical papillae deep to epithelium. Functionally, the filiform and conical papillae appeared to have a mechanical role whereas fungiform, foliate, and vallate papillae apparently perform a gustatory role in the pig. The tonsillar location at the root of the tongue provides an ideal experimental model for immunohistological and immunological studies on the lymphoid tissue in man.     

Immunoelectron microscopic studies on protein gene product 9.5 and calcitonin gene-related peptide in vallate taste cells and related nerves in the guinea pig

On the basis of our previous report that protein gene product 9.5 (PGP 9.5)-immunoreactive nerve fibers and taste cells and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers are found in guinea pig vallate papillae [Huang and Lu (1996b) Arch. Histol. Cytol. 59:433-441]. We speculated that PGP 9.5 might be a marker for taste receptor cells and that CGRP might play an important role in taste transmission. We, therefore, performed an immunohistochemical and ultrastructural analysis of taste cells and related nerves in guinea pig vallate papillae. In the connective tissue of the vallate papilla, the ultrastructural data revealed that the PGP 9.5-immunoreactive nerve fibers were both myelinated and unmyelinated. The CGRP-immunoreactive nerve fibers were unmyelinated and surrounded by the cytoplasm of Schwann cells as were the non-immunoreactive fibers. In the vallate taste buds, only type III cells, which make synaptic contacts with intragemmal nerves, were PGP 9.5-immunoreactive, while the nerve terminals making synaptic contact with the underlying type III cells were CGRP-immunoreactive. From these observations, we conclude that: (1) PGP 9.5 might be a useful specific marker for type III cells in guinea pig vallate taste buds; and (2) CGRP-containing nerve fibers might be primarily involved in the neural transmission of taste stimuli.     

Morphology of the tongue dorsal surface of gilthead seabream (Sparus aurata)

The gilthead seabream is a food fish, one of the most frequently used in aquaculture. In the species of commercial interest, feeding in captivity is very important and this process is strictly related to the morphological characteristics of the oral cavity. The aim of this study is, using the standard procedures for light and scanning electron microscopy, to analyze the morphology of the tongue dorsal surface to show if relationships are present between the tongue morphology and the nutritional habits and choices of this farmed species. The main characteristic of the gilthead seabream oral cavity floor is the presence of an apical pouch, with, probably, a protective role mainly for the apical, free part of the tongue. Three zones, like in other teleosts, an apex, a body and a root, can be clearly distinguished. In the pouch foliate‐like papillae were observed, while the whole tongue is characterized by the presence of two types of papillae, respectively with a fungiform and cylindroid aspect, both randomly distributed throughout the whole dorsal surface of the tongue. Scattered and numerous taste buds, with the typical pear‐onion shape, together with small and numerous taste pores are also present, distributed throughout the tongue surface. Our results demonstrate that in the gilthead seabream important mechanic and sensory roles are carried out by specific anatomical structures. Our anatomical data could give, together with further biochemical and physiological data, an important support with the aim of improving the nutrition of aquaculture species. Microsc. Res. Tech. © 2012 Wiley Periodicals, Inc.     

Macroscopic and microscopic analysis of the tongue of the common opossum (Didelphis marsupialis)

We performed a macroscopic and microscopic study of the tongues of common opossums, Didelphis marsupialis, from South America. We studied two males and two females. We collected morphometric data on the tongue with precision calipers. For the light microscopy and scanning electron microscopy analyses, we fixed tissue fragments in 10% formaldehyde and 2.5% glutaraldehyde, respectively. The opossum tongues averaged 5.87 ± 0.20 cm in length, 3.27 ± 0.15 cm in width at the lingual body, and 3.82 ± 0.15 cm in width at the root. The mean thickness of the lingual body was 1.8 ± 0.1 cm, and the thickness of the root was 3.82 ± 0.15 cm. Sharp filiform papillae were scattered across the entire tongue; conical filiform papillae occurred on the lingual body and tongue tip; fungiform papillae were scattered among the filiform papillae on the lingual body and tongue tip; and there were three vallate papillae at the root of the tongue. We found two strands of papillary projections in the tongue root. Despite the low variability observed in the lingual papillae, the morphological data obtained in this study may be related to the opossum's diverse food habits and the extensive geographic distribution of the species throughout America. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

Functional and comparative study of lingual papillae in four species of bear (Ursidae) by scanning electron microscopy

The eight current species of bear (Ursidae) are widely distributed throughout Europe, Asia, and America. They are mainly encountered in the northern hemisphere, except for the spectacled bear and the sun bear, which are also found in the south of the equator. Adaptations of the masticatory apparatus (teeth, tongue, and musculature) to diet are one of the factors that imply the greatest structural changes in the cranium. This diet may be carnivorous, herbivorous, melliferous, or insectivorous, with one type of food predominating according to the time of year. The way in which food is eaten determines the morphology of the lingual surface; generally speaking, all bears put their mouth to the food, which, initially, they lick or they let the food stick to their tongue, as occurs when insects are eaten. As in all mammals, a distinction can be made between mechanical and gustatory papillae and the development and distribution of which depend on the species and their eating habits. In this study of the complete tongues of four species of adult bears, we describe the morphology of the lingual surfaces, the different types of papillae, their characteristics, and topographic distribution. It was seen that there were five main types of lingual papillae: filiform, conical, fungiform, foliate, and vallate. Morphology of the microgrooves and pores was similar to that observed in other mammals. In general, there were no great differences among the four species of bears studied, perhaps due to the similarity in the kind of food they consume in captivity.     

Morphological structure of rat tongue using light and scanning electron microscopy

The rat is one of the most commonly used animals in biological research and experimental investigations in medicine. The ultrafine structural components of the epithelium differ depending on the anatomy of the animal and the papilla type. Animal adaptation to food types and environmental circumstances may also be linked to morphological diversity. In the current study, seven male Wistar rat tongues were investigated. For scanning electron microscope (SEM), two rat tongues were immersed in a 10% formalin solution and the other two rat tongues were immersed in a 2.5% glutaraldehyde solution. The tongues of three rats were fixed for regular histological evaluation using triple staining. The three primary components of the Wistar rat tongue are the apex, body and root. The apex had a rounded and bifurcated shape. Filiform papillae and gustatory papillae were easily identified on the dorsal side of the tongue. There were three forms of gustatory papillae; fungiform papillae, vallate papillae and foliate papillae. The purpose of this study was to expose the tongue morphology of the Wistar rat species, which is widely used in investigations. Also, we wanted to show that formalin fixation can be utilized for morphological research in SEM. Finally, the Wistar rat tongue was thoroughly investigated and compared to those of other species.     

Morphological tools to evaluate the digestory apparatus in rocky cavy (Kerodon rupestris)

This research describes for the first time the complete morphology of the digestive apparatus of rock cavies. Dissection, light microscopy, and scanning electron microscopy were performed. The oral cavity has: the hard palate without palatine wrinkles and the soft palate; the tongue composed by striated musculature, with presence of vallate, foliated, and fungiform papillae with taste buds and filiform papillae with mechanical function; and, 20 teeth of the hypsodonts type. Esophagus, stomach, small intestine (duodenum, jejunum, and ileum), and the large intestine (cecum, colon, and rectum) are found. The anus is present at the end of the alimentary channel. Organs of digestive tube are composed by four tunics: mucosa, submucosa, muscular, and serosa. The duodenum, jejunum and ileum have villi. Jejunum, ileum and cecum present Lieberkühn crypts. The cecum has mucous glands. Colon and rectum are folded and have goblet cells. Anus presents sebaceous glands. As associated glands it is found the liver with six lobes and gallbladder; a lobulated pancreas; and a pair of each major salivary gland (parotid, mandibular, and sublingual). Parotid glands have serous acini and mandibular and sublingual glands have mucous acini. Pancreas has adenomers. The liver has hepatocytes and portal vein, hepatic artery, and bile duct (portal triad), separated by sinusoids. It is concluded that the digestive apparatus of the rock cavy has variations in the dentition, lingual papillae, and acini of the salivary glands when compared to other rodents. Other variations refer to the well‐developed cecum characteristic of herbivorous behavior.     

Macro‐ and microscopic study on the tongue and lingual papillae of Bison bonasus hybrid as an interspecific species (Bos taurus × Bison bonasus)

Nowadays the processes of crossing of different mammalian species are well characterized in light of genetics, and possibility of reproduction. Generally, lack detailed studies on changes in anatomy and histology of internal systems of hybrids. Bison bonasus hybrid is an interspecific species between the bull of European bison (Bison bonasus), and female of domesticated cattle (Bos taurus). To study the anatomy of tongue and distribution of lingual papillae on Bison bonasus hybrid tongue, a stereomicroscopic and scanning electron microscopic observations was conducted. We aimed to study the appearance of macro‐ and microscopic traits in relation to parental species and other bovids. Results indicate that Bison bonasus hybrid tongue possesses characteristic traits for parental species and ruminants from Bovidae family and also species‐specific features differ from mentioned animals. Specific new traits in hybrid are: V‐shaped arrangement of lingual papillae on ventral surface of the tongue, rosette arrangement of conical papillae on the top of lingual prominence, bigger number of vallate papillae and closer arrangement of vallate papillae. In hybrid observed also the appearance of combination of parental traits. Similar to European bison are rectangular shape of lingual prominence and absence of filiform papillae on the root of tongue. Presence of lateral processes of filiform papillae on the apex of tongue, and arrangement of vallate papillae into two rows corresponded to cattle. Development of new morphological features of tongue and its mucosal papillae in Bison bonasus hybrid opens new issue for future studies on organs of digestive system in animals after hybridization.     

Gross and microscopic observations on the lingual structure of the Franciscana (Pontoporia blainvillei--Gervais and d'Orbigny, 1844)

In most anatomical studies developed with mammals, the tongue is described as highly differentiated among different species. However, studies on the tongue of aquatic mammals are still limited as compared to those on terrestrial mammals. The aim of this study was to describe the tongue morphology of the Franciscana dolphin (Pontoporia blainvillei) using macroscopic observations, light, and scanning electron microscopy. Microscopically, the dorsal surface was covered by a keratinized stratified epithelium. Salivary gland acini were found on the middle and caudal third of the tongue. The dorsal surface was totally covered by filiform papillae with a connective tissue core and a connective tissue structure round in shape in the middle and caudal regions.     

Ultrastructural aspects of Callithrix penicillata lingual papillae

Callithrix penicillata belongs to the family Callitrichidae, Callithrix genus. They are basically insectivorous, but they consume fruits. The mucosa of the tongue is composed of some papillary types, revealing different levels of expertise. The present study attempted to describe the morphological and ultrastructural aspects of the dorsal surface of the C. penicillata, describing the characteristics and distribution of papillae found. Five tongues of C. penicillata (two females and three males), obtained from breeding colonies of CENP-Ananindeua-PA, died from natural causes. The material was fixed partly in a buffer solution paraformaldehyde 10% and partly in modified Karnovsky solution, divided into apex, body, and root, and then the fragments were used in light microscopy and scanning electron microscopy. The average length of the tongue of the females was 22 mm and for males 20.5 mm. Three types of papillae were described: filiform (along all tissue extension with 154 μm of diameter), fungiform (along all tissue extension with 275 μm of diameter), and vallate (just three units in caudal (dorsal) portion with 672 μm of diameter). Data analysis indicates that the distribution and ultrastructural morphology of the C. penicillata lingual papillae are some similar to other primates.     

Ultrastructural aspects of lingual papillae in squirrel monkey (Saimiri sciureus)

Saimiri sciureus is one of the smallest Cebidae native of Amazon region and also found at the biological reserve of northeast Atlantic forest. It is an omnivore animal, with diversified diet that directly influences the lingual mucosa, which includes certain types of papillae with different organization levels. The present study attempted to describe the morphological and ultrastructure aspects of the dorsal surface of the S. sciureus. Five tongues of de S. sciureus were analyzed from three males and two females who died from natural causes and were obtained from breeding colonies of CENP-Ananindeua-PA. Main macroscopic features were a general triangular shape with a craniocaudal elongation pointed apex. Tissue samples--apex, body, and root of tongue--were fixed in modified Karnovsky solution, following standard scanning protocol, mounted in stubs, coated by gold, and analyzed by Scanning Electron Macroscopy (SEM). Four types of papillae were described: filiform (along all tissue extension with 154 μm of diameter), fungiform (along all tissue extension with 272 μm of diameter), vallate [just three units in caudal (dorsal) portion with 830 μm of diameter] and foliate (one pair at caudolateral surface with ～ 13 projections and 3000 μm in length). Data analysis indicates that the distribution and ultra structural morphology of the S. sciureus lingual papillae are some similar to other primates.     

Morphology of the European sea bass (Dicentrarchus labrax) tongue

The European sea bass, a member of the Moronidae family, is a food fish, considered one of the first models for the intensive breeding in salt water. It has nowadays an important and increasing presence in the international fishing markets. Sea basses are carnivorous, feeding on little fishes and invertebrates. Considering the important role of the tongue during the intraoral transport and the swallowing of food, scarce data are present in literature about its morphology. The aim of this study was to analyze the morphology of the tongue by means of scanning electron and light microscopy. Adult sea basses were obtained from the aquarium of the Sicilian Center of Experimental Ichthyiopathology of the University of Messina. The fishes were anaesthetized with MS 222 and the heads were then quickly removed and processed for the paraffin embedding and SEM processing. Three different tongue regions could be distinguished: an apex, a body, and a root. Scanning electron and light microscopy showed the presence of numerous canine-like teeth, surrounded by taste buds and numerous fungiform and conical papillae. The teeth were curved and their tips were posteriorly oriented. The results confirm, in teleosts too, the fundamental role of the tongue in the mechanics of food ingestion. Moreover, the presence of taste buds demonstrates the interaction of food processing and taste. These data could be a potential source to identify new and better methods of nutrition in the breeding of this fish.     

Morphofunctional structure of the lingual papillae in three species of South American Camelids: Alpaca,guanaco, and llama

The aim of this study was to compare the anatomical and functional characteristics of the lingual papilla among the Camelidae. For this purpose, tongues of alpaca, guanaco, and llama were used. Numerous long and thin filiform papillae were located in the median groove and none were detected on the rest of the dorsal surface of the lingual apex in alpaca. Secondary papillae originated from the base of some filiform papillae on the ventral surface of alpaca tongue. The bases of some filiform papillae of the lateral surface of the lingual apex were inserted into conspicuous grooves in guanaco and tips of filiform papillae on the dorsal surface of the lingual body were ended by bifurcated apex. On the dorsal surface of the lingual apex of llama, there were no filiform papillae but there were numerous filiform papillae on both the lateral margins of the ventral surface of the lingual apex. Fungiform papillae were distributed randomly on dorsal lingual surface and ventral margins of the tongues of all camelid species. Lenticular papillae were located on the lingual torus and varied in size and topographical distribution for each species. Circumvallate papillae had irregular surfaces in llama and alpaca, and smooth surface in guanaco. In conclusion, llama and alpaca tongues were more similar to each other, and tongues of all camelid species displayed more similarities to those of Bactrian and dromedary camels in comparison with other herbivores and ruminants. Microsc. Res. Tech. 79:61–71, 2016. © 2015 Wiley Periodicals, Inc.     

Gustatory ultrastructures of an amphihaline migratory fish hilsa Tenualosa ilisha

This study was conducted with the tongue samples of different life stages of hilsa, that is, adult Marine hilsa, adult Riverine hilsa, and Riverine juvenile hilsa, respectively. Three types of taste buds (Types I, II, and III based on their elevation from the epithelium at different levels) of the tongue, which may be to ensure full utilization of the gustatory ability of the fish were rocorded. Presence of specific taste buds indicate that the fish hilsa dwells in turbid waters with a possible preference toward diatom like planktonic food source. Enhanced expression of taste receptors (T1R1 and T1R3) and associated stimulatory G‐proteins subunits on tongue also indicate occurrence of amino acid like substances that guided sensory cues for feeding by this fish. A firm regularity or stringency of the free surface of the epithelial cells may be attributed to compactly arranged microridges. These structures protect against physical abrasions potentially caused during food manoeuvring and swallowing. In our present observations, the surface architectures of the tongue of hilsa are discussed within the background of migratory adaptation of the species in the context of feeding and habitat preferences.     

Morphology of the lingual surface of South American fur seal (Arctocephalus australis) and sea lion (Otaria flavescens)

In this study, we aimed to describe the morphological characteristics of the lingual papillae in two species of Otariidae family by stereomicroscopy and scanning electron microscopy. We used tongues of two South American Otariidae species. The tongues were elongated and terminated in bifid apex and there was no median sulcus on the dorsal lingual surface. The most numerous type of lingual papilla was filiform in the South American fur seal (SASL) and entire dorsal lingual surface was covered by these filiform papillae but the dorsal surface of the tongue of the South American sea lion was covered by numerous polygonal projections, which were different in size. Fungiform papillae were detected in only SASL and they randomly distributed on the lingual apex and body, and some fungiform papillae were collected into twosome or threesome groups on the posterior part of the lingual body. Circumvallate papilla was found in the center of the lingual radix of South American sea lion. Thread‐like conical papillae were common for both species and they located on the lingual radix. We determined that lingual surface morphology was completely different in each species, although they were members of the same family, Otariidae. Microsc. Res. Tech. 78:140–147, 2015. © 2014 Wiley Periodicals, Inc.     

Fine Structure of Bacterial Adhesion to the Epithelial Cell Membranes of the Filiform Papillae of Tongue and Palatine Mucosa of Rodents: A Morphometric,TEM, and HRSEM Study

The palatine mucosa and filiform papillae of the dorsal tongue mucosae of rodents were examined using transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HRSEM). In the HRSEM method, the samples were fixed in 2% osmium tetroxide, dehydrated in alcohol, critical point‐dried, and coated with gold‐palladium. In addition, the HRSEM technique was used for morphometric analysis (length, width, and length/width ratio of cocci and bacilli). For the TEM method, the tissues were fixed in modified Karnovsky solution (2.5% glutaraldehyde, 2% formalin in 0.1M sodium phosphate buffer, pH 7.4) and embedded in Spurr resin. The results demonstrated that there are thick polygonal keratinized epithelial cells where groups of bacteria are revealed in three‐dimensional images on the surface of filiform papillae in these animals. The bacterial membranes are randomly attached to the microplicae surface of epithelial cells. Morphometrics showed higher values of length and width of cocci in newborn (0 day) as compared to newborn (7 days) and adults animals, the bacilli showed no differences in these measurements. At high magnification, the TEM images revealed the presence of glycocalyx microfilaments that constitute a fine adhesion area between bacterial membranes and the membranes of epithelial microplicae cells. In conclusion, the present data revealed the fine fibrillar structures of bacteria that facilitate adhesion to the epithelial cell membranes of the oral cavity and morphometric changes in newborn (0 day) rats as compared with other periods. Microsc. Res. Tech. 76:1226–1233, 2013. © 2013 Wiley Periodicals, Inc.     

Scanning electron microscopic and histological studies of the buccal cavity of a phytoplanktivorous small freshwater fish,Amblypharyngodon mola

The electron microscopic and histological studies of the buccal‐cavity of herbivorous fish Mola (Amblypharyngodon mola) were performed. The studies revealed that the architectures of the buccal cavity of A. mola support the herbivory nature of the fish. Both the upper and lower jaws of the fish are rich in mucus glands, unculi, and microridges. The presence of papillae like taste buds in the lower jaw of A. mola indicates the mechanosensory role of the lower jaw during gustation. These features directly support a gustatory feeding behavior associated with filter feeding in this small freshwater fish.