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OkajimasLingual Folia PapillaeAnat. Jpn., of the87 (2):Common 65–73, August, 201065

Light and Scanning Electron Microscopic Study on the Tongue and Lingual Papillae of the Common raccoon, lotor

By

Yoshiko MIYAWAKI1, Ken YOSHIMURA1, Junji SHINDO2, and Ikuo KAGEYAMA1

1 Department of Anatomy, Faculty of Life Dentistry, The Nippon Dental University at Niigata, Niigata, Japan 2 Laboratory of Wildlife Science, Dept. of Environmental Bioscience, School of Veterinary Medicine, Kitasato University, Towada, Japan

–Received for Publication, June 4, 2010–

Key Words: Common raccoon, carnivore, lingual papillae, comparative anatomy, scanning electron microscopy

Summary: We observed the external surface and connective tissue cores (CTCs), after exfoliation of the epithelium of the lingual papillae (filiform, fungiform, foliate and vallate papillae) of the common raccoon Procyon( lotor) using scanning electron microscopy and light microscopy. The tongue was elongated and their two-third width was almost fixed. Numer- ous filiform papillae were distributed along the anterior two-thirds of the tongue and fungiform papillae were distributed between the filiform papillae. Eight vallate papillae that had a weak circumferential ridge were distributed in a V-shape in the posterior part of the tongue and numerous taste buds were observable in the circumferential furrows of vallate papil- lae. Weak fold-like foliate papillae were observable at the lateral edge in the posterior part of the tongue and a few salivary duct orifices were observable beneath the foliate papillae. An islet-like structure with numerous taste buds, was observable on the deep part of the salivary duct of foliate papillae. Large conical papillae were distributed at the posterior part and root of the tongue. After removal of epithelium, filiform papillae of CTCs were appeared to be a thumb or cone-like main core and associating several finger-like short accessory cores. These cores were surrounded an oval concavity. The main core was situated behind the concavity and associated with accessory cores. CTCs of fungiform papillae were cylinder-like with numerous vertically running ridges and with a few concavities seen at the top of the cores. CTCs of vallate papillae and their surrounded circumferential ridge were covered with numerous pimple-like protrusions. The lingual papillae of Common raccoon’s tongue had morphological feature of carnivore species.

The tongue of mammalian species has morphological composed of several families of -like carnivores, diversity i.e. distribution of the different types of lingual . Arctoid families include: Ursidae () and papillae (Sonntag, 1925). In particular, variations in the Pinnipedia [Phocidae (true or earless seals), Otariidae three-dimensional structures of the lingual papillae and (eared seals), and ()] and Musteroid; their connective tissue cores (CTCs) after removal of (), (), Procyoni- the overlying epithelium. The morphological diversity dae () and () (Delisle and of mammalian species depends on the dietary habits and Strobeck, 2005; Flynn et al., 2005; Fulton and Strobeck, their living environment (Kobayashi et al., 1988a, 1989, 2006). 1992). There have been a number of morphological reports of Among mammalian families, are widely lingual papillae and their connective tissue cores (CTCs), distributed and are traditionally divided at the suborder including several reports among : level into Caniformia, -like carnivores, and Felifor- (Domestic ; Kobayashi et al., 1988b, 1992), (Rac- mia, -like carnivores. Dog-like carnivores, Caniformia coon dogs; Emura et al., 2006, 2008), Ursidae (Japanese are futher subdivided into two infraorders: Cynoidea (or black bears; Inatomi et al., 1999), Phocidae (Spotted Canoidea) comprising a single family, Canidae (dogs seals; Yoshimura et al., 2007) and Otariidae (California and ), sister to Arctoidea, a more diverse infraorder sea ; Yoshimura et al., 2002), Musteroidea; Ailuridae

Corresponding author: Ken Yoshimura, Dept. of Anatomy, Faculty of Life dentistry, The Nippon Dental University at Niigata, 1-8 Hamaura-cho, Chuo-ku, Niigata City, Niigata, 951-8580 Japan. E-mail: [email protected] 66 Y. Miyawaki et al.

(Red Panda; Emura et al., 2009) and Mustelidae (Japanese ; Yoshimura et al., 2009, Japanese ; Emura et al., 2007), however, investigations of lingual papillae of the ’s tongue have yet to be reported. The aim of this study was to investigate both the three-dimensional structures on the surface of the lingual papillae and their CTCs after exfoliation of the epithe- lium on the dorsal surface of tongue in detail of a Procy- onidae’s species, namely the Common raccoon (Procyon lotor).

Materials and Methods

Tissue specimens and preparation Five adult tongues of Common raccoons (Procyon lotor; four males and one female.) (Body length: 97–140 cm, Body weight: 26–28 kg) that died in extermination programs of invasive alien species were used for this study. Specimens were fixed with 10% formalin for post- mortem autopsy. Shortly afterwards, blocks were then cut from various parts of the tongue. Fig. 1. a: Overview of the dorsal surface of the tongue of the Com- mon raccoon (Procyon lotor). Scale bar = 1 cm, b: Diagram of Light microscopy the tongue; A: Apex, B: Anterior/Middle part. C: Posterior part. For light microscopy, specimens were dehydrated D: Root. Fi: Filiform papilla, Fo: Foliate papilla, Fu: Fungiform with a graded series of alcohol. Following dehydration, papilla, VP: Vallate papilla. specimens were embedded with paraffin and sectioned four micrometers thick. Sections were stained with hematoxylin-eosin (H-E). These slides were observed with a light-field microscope (BH-2, Olympus, Japan). papillae [Fig. 1; Fu] were distributed in the apex [Fig.1b; A], anterior [Fig.1b; B] and posterior part [Fig.1b; C]. Scanning Electron Microscopy Eight vallate papillae [Fig. 1b; VP] were distributed in For scanning electron microscopy, specimens were a V-shape in the posterior part [Fig.1b; C]. Weak fold- immersed in 3.5N-HCl for five days at 32°C. After im- like foliate papillae were observable at the lateral edge in mersion of the specimens, the epithelium was exfoliated the posterior part [Fig.1b; C] where a few orifices were from the underlying CTCs at the boundary of epithelium- found. Large conical papillae were distributed at the connective tissue layer. Specimens were washed with tap posterior part [Fig.1b; C] and root of the tongue [Fig.1b; water, and then treated with a 0.5% tannic acid solution. D]. Toward the posterior, large conical papillae increased Post fixation was accomplished by a ten-minute immer- in their size. sion in a 1% OsO4 solution. Specimens were then washed and dehydrated with a graded series of ethanol. 2) Microscopic Observation After dehydration, specimens were freeze-dried with a a) Filiform Papillae t-butyl alcohol freeze-drying method (Inoue and Osatake, Under lightmicroscopy, the epithelium of filiform 1988). Before observation, specimens were coated with papillae exhibited ortho-keratinization and had a thick Pt-Pd, and then observed with a scanning electron micro- stratum corneum, especially on the anterior part of scope (S-800, Hitachi-Hi-Technologies, Japan). the papilla with keratohyaline granules being observ- able [Fig. 2d; arrow] in the anterior part. No lingual glands were observable in the lamina propria of the Results anterior/middle part of the tongue, however, serous- rich lingual glands were found in the posterior part. 1) Macroscopic Overview Under scanning electron microscopic observation, In the macroscopic images, tongues of the Common the external appearance of the filiform papillae had a raccoon [Fig. 1] were elongated and their two-third width thick main conical protrusion and was associated with was almost fixed. A lingual prominence was absent. 7–20 accessory protrusions. In front of the filiform Numerous filiform papillae [Fig. 1; Fi] were distributed papilla, main protrusion appeared to be somewhat along the anterior two-thirds of the tongue. Fungiform concaved. Among the accessory protrusions, long pro- Lingual Papillae of the Common raccoon 67

Fig. 2. A set of lingual papillae distributed on the apex (indicated as “A” on Fig. 1b) part of the tongue. a: Light micrograph of fungiform papil- lae distributed on the apex of tongue (sagittal section). Taste buds (indicated as arrows) were observable on the top of the papilla. Scale bar = 100 µm. b: Scanning electron micrograph of the external surface of fungiform papilla situated on the apical part of tongue. Scale bar = 100 µm. c: SEM micrograph of the connective tissue core (CTC) of a fungiform papilla after epithelial exfoliated. Cylinder-like CTC was observable after removal of the epithelium. Several concavities were also seen at the top of the CTC. Scale bar = 100 µm. d: Light micro- graph of filiform papillae situated on the apical part (sagittal section). Thick stratum corneum of filiform papillae was seen. Keratohyalin granules were observable at the front part of the papillae (arrow). Scale bar = 100 µm. e: SEM micrograph of the epithelial surface of filiform papillae situated on the apical part of tongue. Main conical protrusion of filiform papillae inclined towards the posterior direction. Accessory protrusions appeared to be surrounding each main protrusion. Scale bar = 100 µm. f: CTCs of the filiform papillae in the apical part of the tongue after removal of the epithelium. A main thumb-like CTC and accessory CTC were surrounded by concavity in front of the papilla. Scale bar = 100 µm. 68 Y. Miyawaki et al.

trusions were studded from the basal part in front of associating several finger-like short accessory cores the filiform papilla and short ones were situated from [Fig. 2f]. These CTCs were surrounded oval concav- the edge of the main protrusion [Fig. 2e and Fig. 3b]. ity. The filiform CTCs that were distributed on the an- Compared with filiform papillae that were distributed terior/middle part of the tongue appeared to be slightly on the apical part, filiform papillae that were situated different. The main core was conical-like with a sharp on the anterior/middle part of the tongue had appeared tip. The accessory cores that were situated in front of to be slightly different; main protrusions was broader the concavity were short finger like. [Fig. 3] On the and elongated, had rather round tip, increased their other hand, a few accessory cores that were situated width and accessory protrusions were situated mostly near the main CTC were short cone-like. The basal from the edge of the main protrusion [Fig. 3b]. part of main CTC had some wrinkles and seemed to After exfoliation of the epithelium, CTCs of fili- merge with a few neighboring accessory cores. form papilla appeared to be thumb-like main core and The filiform papillae were approximately 358–870

Fig. 3. A set of filiform papillae distributed on the anterior/middle (indicated as “B” on the Fig. 1b) part of the tongue. a: Light micrograph of filiform papillae distributed on the anterior/middle part of tongue (sagittal section). Each papillae was somewhat elongated. Scale bar = 100 µm. b: SEM micrograph of the epithelial surface of filiform papillae that were situated on the anterior/middle part of the tongue. Main protrusions were relatively broader compared with those on the apical part. Scale bar = 100 µm. c: SEM micrograph of the CTCs of the filiform papillae of anterior/middle part after removal of the epithelium. Main protrusion of filiform CTCs in this area appeared to have a sharp tip. Scale bar = 100 µm. Lingual Papillae of the Common raccoon 69

µm long and 147–311 µm wide. d) Vallate papillae b) Fungiform Papillae Eight vallate papillae were arranged in a V-shape Under lightmicroscopy, the top of the fungiform in the posterior part of the tongue. Under lightmicros- papillae [Fig. 2a] were dome-like and had a thin stra- copy, several taste buds were distributed in the inner tum corneum with a few taste buds observable in the wall of the epithelial circumferential furrow [Fig. epithelium of the fungiform top. 5a]. In the lamina propria, serous lingual glands were In SEM observations, the external surface of fungi- observable with their orifices opening into the furrow. form papillae distributed on the anterior part of tongue In SEM observations revealed that a weak circum- were smooth and dome-like on the fungiform top [Fig. ferential ridge around the Vallate papillae. The surface 2b]. of the papilla contained of some bump-like protru- After removal of the epithelium, CTCs of fungi- sions [Fig. 5d]. form papillae appeared cylinder-like [Fig. 2c] with After exfoliation of the epithelium, the CTCs of numerous vertical ridges. A few concavities were also vallate papillae were covered with numerous pimple- seen at the top of the CTC. Among fungiform CTCs like protrusions. These pimple-like protrusions were that were distributed on the middle part of the tongue, also found in the surrounding circumferential ridge. some of the concavities were deep and seemed to be Vallate papillae were approximately 796–1157 µm in cleft-like. The fungiform papillae were approximately diameter. 173–335 µm in diameter. e) Large conical papillae in the lingual root c) Foliate papillae Large conical papillae were distributed in the A few salivary duct orifices were observable at posterior part and root of the tongue. Lightmicro- the lateral side of the posterior part of the tongue. scopically, no salivary glands were observable in the Under lightmicroscopy, an islet-like structure with lamina propria of this area [Fig. 5d]. numerous taste buds was observable on the deep part SEM observations revealed that the external sur- of this duct. Beside the islet, ducts connected into the face of the conical papillae distributed in the root of salivary gland [Fig. 4a]. tongue was smooth and similar to surrounding epithe- SEM observations revealed shallow fold-like papil- lium [Fig. 5e]. lae on the epithelial surface around the orifices. After After removal of the epithelium, the appearance of removal of the epithelium, several CTC ridges were CTCs of the large conical papillae was totally different running vertically [Fig. 4b]. from CTCs of filiform papillae. CTCs of large conical shaped papillae were covered with numerous pimple-

Fig. 4. A set of foliate papillae (indicated as “Fo” on Fig. 1b) distributed on the posterior (indicated as “C” on Fig. 1b) of the tongue. a: Light micrograph (horizontal section) of foliate papillae situated on the posterior area. An orifice (arrow) was seen. Deep part of this duct, an islet-like structure with numerous taste buds, was observable. Scale bar = 200 µm. b: SEM micrograph of the CTC of the foliate papilla in the posterior area after partially removal (left half side) of the epithelium. A large orifice (arrow) was seen at the lateral side of the tongue. Some of the ridges were also observable. Scale bar = 1000 µm. 70 Y. Miyawaki et al.

Fig. 5. A set of vallate papillae (indicated as “VP” on Fig. 1b) distributed on the posterior (indicated as “C” on Fig. 1b) of the tongue and large conical papillae distributed on the root (indicated as “D” on Fig. 1b) of the tongue. a: Lightmicrograph of a vallate papilla (sagittal sec- tion). Some taste buds (arrows) were found in the inner wall of the epithelial furrow. In the lamina propria, Von Ebner glands (S) were seen. Scale bar = 200 µm. b: SEM micrograph of the epithelial surface of a vallate papilla. A weak circumferential ridge of Vallate papilla was observable. Scale bar = 400 µm. c: SEM micrograph of the vallate papilla that was partially exfoliated (upper part of their epithelium). Numerous pimple-like protrusions were distributed on the Vallate CTC and their surrounded circumferential ridge. Scale bar = 400 µm. d: Lightmicrograph of the root area (sagittal section). A large conical papilla was present. No salivary glands were observable on the lamina propria of this area. Scale bar = 200 µm. e: SEM micrograph of epithelial surface of root area. Surface of the large conical papillae was smooth and similar to surrounding epithelia. Scale bar = 200 µm. f: SEM micrograph of posterior part of after epithelial exfoliation. CTCs of large conical papillae were covered with numerous pimple-like protrusions, however, these pimple-like protrusions diminished towards the uppermost quarter. Scale bar = 200 µm. Lingual Papillae of the Common raccoon 71

like protrusions, however, these pimple-like protru- raccoon might be representative of an omnivorous-like sions diminished especially on the uppermost quarter diet and/or masticatory method. of each large conical CTCs [Fig. 5f]. The length of the CTCs of filiform papillae of the Common raccoon conical-shaped papillae was approximately 797–2229 consisted from thumb or cone-like main core, oval µm and width was 317–1187 µm. concavity and several finger-like short accessory cores. Behind the concavity, was situated a main core and was surrounded accessory cores. Filiform CTC of other Arc- Discussion toid species such as the Japanese black bear (Inatomi and Kobayashi, 1999) exhibit quite similar characteristics to Procyonidae (raccoons) are categorized as Arctoidea, those found in the common raccoon. Filiform CTC of bear-like carnivores and in the more diverse infraorder the Japanese black bear have a circular concavity and are including bears, red panda, skunks, weasels and pin- surrounded by ten or more small rod-like cores. Cores nipedia. In this study, we examined various aspects of the that were situated posteriorly were comparatively thick, lingual papillae of the Common raccoon’s tongue. long and inclined toward posterior. CTC of filiform papillae of the red panda (Emura et al., 2009) appear Lingual papillae and their connective tissue cores to have a main CTC that consists of a few cores and a The tongue of the Common raccoon had each of the few small accessory cores surrounding the concavity. following lingual papillae: filiform, fungiform, conical, Filiform CTC of Japanese badgers (Yoshimura et al., foliate and vallate papillae. In the present observation, 2009) have a main slender core and ovally arranged (10 the external appearance of the filiform papillae, in the or more) short accessory protrusions distributed around Common raccoon was that of a thick main conical the main core. Despite an unclear micrograph of the protrusion with 7–20 accessory protrusions. Reports filiform papillae CTC of the ’s tongue regarding other Arctoid species, e.g. Japanese black bear (Emura et al., 2007), several small processes were (Inatomi and Kobayashi, 1999), the epithelial surface of observable surrounded by circular or oval concavities. filiform papillae appeared as a sharp conical main pro- CTC of filiform papillae in seem to be varied trusion with 8–12 accessory protrusions. The epithelial compared with those in the terrestrial Arctoid; where surface of filiform papillae in red pandas (Emura et al., CTCs of filiform papillae appear thick conical shaped 2009) has been shown to consist of one thick ‘shovel- with numerous small, studded projections but no con- like’ conical protrusion with several associated protru- cavities were found in front of the CTCs [California sea sions. Filiform papillae of Japanese badgers (Yoshimura lion; Yoshimura et al., (2002)]. In contrast, filiform CTCs et al., 2009) have been reported to be rather thick conical of the exhibit a primary core associated with shaped with several accessory protrusions distributed on approximately 5–15 accessory cores (Yoshimura et al., the main protrusions. In the Japanese Marten’s tongue 2007) and are comparatively similar to terrestrial Arctoid (Emura et al., 2007), the epithelial surface of filiform species. Filiform CTC of Canidae, sister clade of Arctoi- papillae exhibit a main protrusion covered with several dea, morphology also resembles that of the domestic dog small processes. In regards to the morphology of filiform with an oval concavity and a main protrusion situated on papillae in pinnipededia species, this is somewhat differ- the posterior end of concavity (Kobayashi et al., 1992). ent; the surface of filiform papillae is clear and conical Several small processes surrounded an oval concavity shaped and accessory processes are not present [Spotted with the main protrusion however being comparatively seal; Yoshimura et al. (2007), California ; sharp and horizontally bending toward posterior. Other Yoshimura et al. (2002)]. A smooth epithelial surface Canidae species such as the (Emura et al., of filiform papillae lacking accessory processes might 2008) also possess a sharp main core warping posteriorly. be represent some kind of oral adaptation for an aquatic CTCs of fungiform papillae of the Common raccoon environment involving e.g. swallowing a smooth texture were cylinder-like and had numerous ridges running diet (like fish or cephalopods). On the other hand, the vertically. Among other Arctoid species, the presence of morphology of the epithelial surface of filiform papillae fungiform CTC vary; fungiform CTCs of the Japanese of Canidae, sister of Arctoidea, domestic dog (Kobayashi black bear (Inatomi and Kobayashi, 1999) are swollen et al., 1988b, 1992) appear to be similar to those in the and spindle-like. CTCs of fungiform papillae in the Arctoidea; with a sharp main conical protrusion and sev- tongue of Red Pandas (Emura et al., 2009) and Japanese eral thin and small processes studded from the edge of Badgers (Yoshimura et al., 2009) are slender columnar- protrusion. In other Canidae species such as the Raccoon like with numerous ridges running vertically on the co- dog (Emura et al., 2006), filiform papillae were almost lumnar-like CTC. Fungiform CTCs of Japanese Marten identical with those of the Common raccoon ie filiform (Emura et al., 2007) seem to have diminished height papillae consisted of main protrusions that were covered and exhibit bulbous cores with associated numerous with several small processes. The similar morphology of ridges running vertically on the CTC. The morphology filiform papillae between the Raccoon dog and Common of fungiform CTCs of Pinnipeds also varies; fungiform 72 Y. Miyawaki et al.

CTCs of the (Yoshimura et al., 2002) papillae (Sonntag, 1925). Most of the vallate papillae have a bulbous appearance with numerous small rod-like between Canidae and Arctoidea have a circumferential secondary cores being densely distributed on its surface. ridge except for the Pinnipedia, i.e. California Sea lion CTCs of fungiform papillae on the spotted seal’s tongue and Spotted Seal (Yoshimura et al., 2002, 2007). (Yoshimura et al., 2007) appear as a cylindrical primary In our present observations regarding the Common core with numerous rod-shaped accessory protrusions Raccoon’s tongue, large conical papillae were distributed arranged on the lateral side of the cylindrical cores. at the posterior part and root of the tongue. As for the Fungiform CTCs of the spotted seal had similarity with Japanese black bear (Inatomi and Kobayashi, 1999), those in the Red panda and/or Japanese . CTC of they possess thick and wide based conical papillae that the domestic dog (Canidae, sister taxa of Arctoidea) have are inclined toward posterior. In the micrographic report a bulbous and dome-like appearance with a few concavi- of the Red panda’s tongue (Emura et al., 2009), similar ties situated on the top of CTC (Kobayashi et al., 1992). cone-like large conical papillae were observed. Japanese In other Canidae such as the Raccoon dog (Emura et al., badger’s have rather long conical papillae (Yoshimura 2008), fungiform CTCs are quite similar to the Japanese et al., 2009) with a main core and numerous small pro- badger’s fungiform CTCs being slender columnar-like trusions. Regarding ’s tongue, spindle-shaped and having numerous ridges running vertically on a large conical papillae are found in the lingual root of columnar-CTC. California sea lion (Yoshimura et al., 2002). Which after In our present observation of the Common raccoon, removal of the epithelium, CTCs of conical papillae are foliate papillae, consisted of a shallow ridge and groove entirely covered with small rod-shaped protrusions of with a few orifices of serous lingual glands. The lateral secondary cores. In the contrast, the Spotted seal lacked organs, or foliate papillae, consist of a numbers of fis- large conical papillae (Yoshimura et al., 2007). A Cani- sures and elevations at the posterior extremity of the free dae such as the Raccoon dog, sister taxa of Arctoidea, part of each lateral border of the tongue (Sonntag, 1920). Emura et al. (2009) have reported in a photograph of These gustatory organs are found only in , but their macroscopic observation cone-shaped large conical not in all species (Sonntag, 1925). Foliate papillae are papillae. absent in ruminants, are rudimentary and lack taste buds in (Frappier, 2006), and are extremely small in the Diet of Arctoid species dog (Nickel et al., 1979). In the review of Kobayashi Arctoidea are bear-like carnivores with variety of (1992), three or so giant conical or finger-like lateral diverse infraorders; Bears (Ursidae) include the world’s organs have been described to exist in the cat, whereas in largest terrestrial carnivores: Grizzly and Polar bears. the dog no taste buds could be found. The Japanese black Bears are largely herbivorous, as the build and the ar- bear’s foliate papillae (Inatomi and Kobayashi, 1999) rangement of their teeth suggest, although they may take has ten grooves and ridges with numerous taste buds and meat occasionally. The one exception is the , orifices of salivary gland opening at the bottom ofthe which feeds primary on seals. On the other hand the groove. ’s tongue lack obvious foliate ’s diet is omnivorous, feeding mainly papillae or taste buds. Instead of foliate papillae, they on plant material, especially nuts and fruit, but also ants exhibit a serrated lateral organ without taste buds that and larvae. Red Pandas have a varied, mainly vegetarian consists of wedge-shaped protrusions (Yoshimura et al., diet of: fruit, roots, bamboo shoots, acorn and lichens 2009). Other Mustelids, such as the and Siberian are reportedly eaten, but it is likely that in the wild they have large-conical like papillae in place of foliate eat also some insects or carrion (Macdonald, 1985). papillae (Emura, 2008). Japanese Marten (Emura et al., The diet of Japanese Badgers is omnivorous with main 2007) and Raccoon dogs (Emura et al., 2006) have foli- foods being eaten: earthworms, insects (Yamamoto, ate papillae and taste buds have been found in the foliate 1991, 1994), and also fruits (Tanaka, 2005). The Marten papillae of the (Furubayashi et al., is omnivorous and main foods are small vertebrates, 1989). especially mice, squirrels, rabbits, and grouse. Carrion is Eight vallate papillae were arranged in a V-shape in also important in their diet, as are fruits and nuts when the Common raccoons. Japanese black bear’s (Inatomi abundant (Macdonald, 1985). Regarding the diet of Pinni­ and Kobayashi, 1999) have 7–10, Japanese badgers’ pedia, California sea feed on squid, octopus, and tongue have seven, and Red Panda’s (Emura et al., 2009) many species of fish and Spotted Seal feed on fish, larger have ten vallate papillae arranged in a V-shape. Ferret crustaceans, octopi and cephalopods (Jefferson et al., and Japanese weasels (Emura, 2007, 2008) have four and 1993). Therefore, except Pinnipedia, most of Arctoid the (Emura, 2008) has six vallate papil- species are nowadays ominivorous. This tendency is also lae. Pinnipeds such as the California sea lion have five seen in the other clade; i.e Canidae; the diet of Raccoon vallate papillae (Yoshimura et al., 2002) and the Spotted dog is omnivorous and various foods eaten: fruits, insects seal has 6–7 vallate papillae (Yoshimura et al., 2007) and other vertebrates, occasional vertebrates and, where arranged in a V-shape. Domestic dogs have 4–7 vallate available, marine invertebrates caught while beach Lingual Papillae of the Common raccoon 73 combing (Macdonald 1985). The present investigation on the Tongue and Lingual Papillae of the Japanese black bear revealed that Procyonidae (raccoon’s) tongue basically (Carnivora) and the Mountain goat (Artiodactyla). Odontology 1999; 87:313–328. resembles not only other Arctoid species but also shares 13) Inoue T and Osatake H. A new drying method of biological some characteristics with the sister taxa, Canidae. 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