81 Braz. J. vet. Res. anim. Sci., São Paulo, v. 44, suplemento, p. 82-88, 2007 Anatomic study and distribution of the Vallate papillae in domestic cats 1 - Faculdade de Ciências Agrárias e Veterinárias da Universidade Estadual Paulista, Jaboticabal-SP 2 - Faculdade de Medicina Veterinária da Universidade Federal de Uberlândia, Uberlândia-MG 3 - Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo, São Paulo-SP Gregório Corrêa GUIMARÃES1 Márcia Rita Fernandes MACHADO1 André Luiz Quagliatto SANTOS2 Maria Angélica MIGLINO3 Correspondência para: Departamento de Morfologia e Fisiologia Animal da Faculdade de Ciências Agrárias e Veterinárias, UNESP, Campus de Jaboticabal. Via de Acesso Professor Paulo Donato Castellane, s/n. 14884-900. Jaboticabal - SP. e-mail: gregorio@fcav.unesp.br Recebido para publicação: 11/10/2005 Aprovado para publicação: 23/08/2007 Abstract The tongue of domestic animals varies in size and shape and according to these animals feeding habits, there are different degrees of tongue surface specialization. At the dorsal surface of the tongue lingual papillae can be observed, such as the vallate papillae, related to taste perception. With the help of a magnifying glass, differences in the number, size and distribution of vallate papillae were studied. Fifty five tongues of adult domestic cats from both sexes (38 females and 17 males) were analyzed. The samples were fixed in 10% buffered formalin. The vallate papillae were found to be symmetrically distributed on 21 tongues (38.18%). However, it was observed that in some of the tongues the number of vallate papillae varied when one side of the tongue was compared to its contralateral side. The vallate papillae showed different shapes: elongated (42.58%), oval (31.61%), round (25.48%) and pear shaped (0.33%). The vallate papillae were classified into 10 different categories: symmetrical I (2 right and 2 left), II (3:3), III (4:4) and asymmetrical IV (3:2), V (4:2), VI (2:3), VII (4:3), VIII (5:3), IX (3:4) and X (4:5). Measurements of length and width were made with averages of 0.84 ± 0.23 mm and 0.55 ± 0.18 mm, respectively, besides the calculation of the total area of these papillae per tongue, that showed average of 2,74 ± 0,31 mm2 in males and 1,94 ± 0,14 mm2 in females However, upon examining the lingual papillae of the cat tongues, specimens demonstrating 7, 8 or 9 vallate papillae, arranged in pairs (4:3, 5:3, 3:4 and 4:5) by category, were observed in this study but not cited in the literature. Key words: Tongue. Vallate papillae. Gustatory papillae. Introduction The tongue of mammals is an important tactile organ contributing significantly to food apprehension. It varies in form and size and demonstrates morphologic diversity that is greatly influenced by feedings habits.1,2,3 The dorsal surface of the tongue in domestic mammals is rough due to the presence of structures called lingual papillae.4,5 These papillae are classified as: filiform, lenticular, conical, foliate, fungiform and vallate, each one possessing different functions.2,3,4,5,6,7,8,9,10 Filiform, lenticular and conical papillae possess a protective and mechanical function. The fungiform, foliate and vallate papillae are related to taste perception2,3,10 and, according to Sonntag5 the foliate papillae are mechanical. The present study focused on the vallate papillae founded in cats, dogs, pigs, cattle and horses.2,5,11 They are located in the caudal third of the tongue3,4,6,12,13,14,15,16,17, on the dorsal face of the tongue’s root3,6,16. In domestic mammals, the vallate papillae are wrapped in a groove that follows their specific shape. Ducts open from serous 82 Braz. J. vet. Res. anim. Sci., São Paulo, v. 44, suplemento, p. 82-88, 2007 glands that help to clean the groove with their secretion.4,6,11,12,14 Particularly in cats, dogs and wild carnivores the vallate papillae are distributed in two convergent lines forming a “V”, with the point of the V directed toward the base.3,4,7,8,9,10,13,16,17 This arrangement occurs when an even number of these papillae are present in symmetrical form. Whenever there is an odd number (three or five), they are asymmetrically arranged.4 This arrangement is described as typical and atypical by Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9. Cats7,8,9 and dogs4 do not have medial vallate papillae. In dogs, when the papillae are arranged asymmetrically, the V arrangement is absent.4 The number of vallate papillae may vary in cats from four to six17,18,19 or four to eight7,8,9. In dogs there may be three to six vallate papillae4 or four to six3,13,14,15,16. These papillae are arranged in pairs of three in the Beagle breed.10 In dogs the vallate papillae have diameters between 1.5 to 2.5 mm.4 The present study was carried out with the intention of obtaining more information on shape, dimension and distribution of vallate papillae in the tongue of the domestic cat, so as to increment anatomical information on this specie. Material and Method Fifty five tongues of unknown breed adult domestic cats were studied, being 38 female and 17 male. They proceeded from the Regional Center of Zoonosis Control of Uberaba, Minas Gerais State - Brazil, and were fixed and immersed in 10% buffered formalin immediately after death. With the help of a magnifying glass the length and width of the vallate papillae were measured using a paquimeter (Mitutoyo®) and each of the vallate papillae was classified as oval, round, elongated or pear shaped. The vallate papipllae’s area were calculated by the application of the formula A = p.a.b (ellipsoid’s area). This formula can’t be applied to the pear shaped papillae with high precision, but this morphological difference was minimized by its low frequency of occurrence. For the number and distribution analysis of the vallate papillae, all tongues had their papillae numbered and classified into two distributions, described as symmetrical and asymmetrical. The symmetrical forms were those that presented the vallate papillae in equal numbers on each side of tongue. These were classified as types I (two on the right side and two on the left side), II (3:3) and III (4:4). The asymmetrical forms were those with papillae distributed in different numbers when both sides of the tongue were compared. These were classified as types IV (3:2), V (4:2), VI (2:3), VII (4:3), VIII (5:3), IX (3:4) and X (4:5). In the descriptive statistical analysis the absolute and relative frequencies of the vallate papillae were calculated. It was applied the t- Student test to compare the values found to the vallate papillae’s area and the number of these papillaes per tongue in accordance with the gender of the animals. The qui-quadrado test was done to compare the values obtained for the types of distribution of vallate papillae. Both of these two statistical tests using S.A.S.® (Software Analysis System). Results The vallate papillae in the cat tongues presented an average of 5.64 ± 1.13 papillae/ tongue (5.65 ± 1.17 in males and 5.63 ± 1.13 in females). The number of these papillae vary from two (30.91% on the right side and 41.82% on the left side), three (47.27% on the right side and 47.27% on the left side), four (20.00% on the right side and 9.09% on the left side), or five (1.82% on the right side and 1.82% on the left side) vallate papillae (Figures 1, 2 and 3). The papillae shape observed varied between elongated (42.58%), oval (31.61%), round (25.48%) and pear shaped (0.33%). In all cases observed, they were surrounded by a groove that conformed to the papillae’s shape (Figure 4). The distribution of vallate papillae and their respective frequencies are presented in figure 2. 83 Braz. J. vet. Res. anim. Sci., São Paulo, v. 44, suplemento, p. 82-88, 2007 Figure 1 - Image of the dorsal surface of caudal third of cat tongue demonstrating vallate papillae (arrows) distribution (type x) no o f c as es (4) (5) (5) (6) (6) (7) (7) (8) (8) (9) Figure 2 - Number of vallate papillae and % (n=55) by type of distribution on cat tongues The arrangement of the vallate papillae classified previously as symmetrical, was found in 38.18% of the animals, 21.82% in females and 16.36% in males. The asymmetrical forms were found in 61.82% of the tongues, being 47.27% from females and 14.55% from males (Figure 3). Measurements of length and width were made, showing an average of 0.84 ± 0.23 mm for length and 0.55 ± 0.18 mm for width of vallate papillae observed. The total area of these papillae per tongue was 2,74 ± 0,31 mm2 in males and 1,94 ± 0,14 mm2 in females (Figure 5). 84 Braz. J. vet. Res. anim. Sci., São Paulo, v. 44, suplemento, p. 82-88, 2007 Figure 3 - Localization of vallate papillae in different distributions on the dorsal surface of the cat tongue, with emphasis on the symmetrical (*) and asymmetrical arrangements Figure 5 - Total area of cat’s tongues vallate papillae in accordance with the gender Figure 4 - Observed shapes of the vallate papillae on cat tongues 85 Braz. J. vet. Res. anim. Sci., São Paulo, v. 44, suplemento, p. 82-88, 2007 There was no significant difference (p>0.05) as for the type of symmetrical and asymmetrical distribution of the vallate papillae, as for the number of these papillae per tongue considering males and females, and also as for the number of these papillae in each side of the tongue; however, the average of the total area of these papillae per tongue showed a significant statistically difference (p 0.05) when compared the gender of the animals. Discussion Information in current literature regarding vallate papillae of the domestic cat is in agreement with the present study, however few references exist as to the characteristics of these papillae in the specie studied. In all of the tongues examined, the vallate papillae, located on the basal third of the tongue dorsum, were surrounded by a groove that conformed to the papillae’s shape. The findings of the present study are also in accordance with the reports from Hudson and Hamilton17, Tichý20, Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9. When these papillae appear symmetrically on the cats’ tongues they are arranged in two lines forming a rostrally open V on the lingual root, similar to those described in cats by Hudson and Hamilton17, Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9. However, when the papillae appear asymmetrically, the V is not clear, the papillae are arranged in two convergent lines. Considering the vallate papillae shapes, the descriptions of the present study are in agreement with the findings of Tichý20, Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9 in cats. According to the first and second authors, these papillae were identified as being oval and spherical, round elliptical and elliptical. The last author identified them as being oval, elongated oval and circular in shape. In the present study these papillae were denominated as being elongated, oval and round. Besides those, the pear shape was also identified. Their size varied according to their localization, where the largest papillae were found by Tichý20 near the lateral margin of the lingual dorsum, but their size decreased towards the median grove. Ojima et al.9 described these papillae as being large or small in size. In the literature consulted on cats no data as to length, width and area of the vallate papillae were found. These measurements were made in the present study, demonstrating an average of 0.84 ± 0.23 mm for length and 0.55 ± 0.18 mm for width, showing total area per tongue of 2,74 ± 0,31 mm2 in males and 1,94 ± 0,14 mm2 in females. The number of vallate papillae found in the animals studied coincides with those described in cats by Crouch18, Kobayashi et al.19 and Hudson and Hamilton17. They described the occurrence of four to six papillae on each tongue, but is possible to observe four to eight papillae Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9 on each tongue. However, one case with nine papillae was also observed in the present study. As to the distribution of the cats’ vallate papillae, it was reported total of two (7.0%7, 13.0%8 and 24.0%9), three (82.0%7, 71.0%8 and 62.0%9) and four (11.0%7, 16.0%8 and 14.0%9) on the right side of the tongue and two (14.0%7, 21.0%8 and 28.0%9), three (79.0%7, 66.0%8 and 62.0%9) and four (7.0%7, 13.0%8 and 10.0%9) on the left side of the tongue. In the present study, cases with two papillae on the right side were 24.0%, 18.0% and 7.0% more frequent than those described by Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9 respectively. The cases with three papillae were 42.0%, 24.0% and 15.0% less frequent than Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9 respectively, and cases with four papillae were 9.0%, 4.0% and 6.0% more, respectively, on the right side, from those reported by the researchers cited. Cases of five papillae (1.8%) on the right and the left side were also observed. The vallate papillae were described by Ojima7 as being found in three typical distributions (2:2, 3:3 and 4:4) and two ≥ 86 Braz. J. vet. Res. anim. Sci., São Paulo, v. 44, suplemento, p. 82-88, 2007 atypical distributions (3:2, 4:2). Ojima, Takeda and Matsumoto8 and Ojima et al.9 described one additional type of atypical distribution (2:3). Ojima7 found the following frequencies of the typical cases: 2:2 (8.0%), 3:3 (76.0%), 4:4 (8.0%) and for the atypical cases: 3:2 (4.0%) and 4:2 (4.0%). However, Ojima, Takeda and Matsumoto8 and Ojima et al.9 found, respectively, 2:2 (11.0% and 11.0%), 3:3 (62.0% and 50.0%), 4:4 (13.0% and 10.0%), 3:2 (8.0% and 11.0%), 4:2 (3.0% and 7.0%) and 2:3 (3.0% and 11.0%). The tongues studied showed four other types of pattern besides the five and six patterns described by Ojima7, Ojima, Takeda and Matsumoto8 and Ojima et al.9. They were classified as asymmetrical (3:4, 4:3, 5:3 and 4:5) appearing respectively in 7.27%, 7.27%, 1.82% and 1.82% of the animals. Conclusion The data provided in the present study demonstrate the numerical variation and general arrangement of the vallate papillae, demonstrating particular aspects of their distribution in domestic cats. Estudo anatômico e distribuição das papilas valadas no gato doméstico Resumo A morfologia descritiva e topográfica, bem como, a distribuição, o número e o tamanho das papilas valadas foram estudados na língua de 55 gatos adultos, sem raça definida, 38 fêmeas e 17 machos, após fixação do material em solução aquosa de formaldeído a 10%. As papilas valadas se distribuíram simetricamente em 21 línguas (38,18%). Estas papilas apresentaram-se sob diferentes formas: afiladas (42,58%), ovaladas (31,61%), arredondadas (25,48%) e com formato de pêra (0,33%). A distribuição das papilas valadas foi classificada em 10 diferentes tipos de acordo com o número de papilas por antímero: I (2 papilas no antímero direito e 2 no antímero esquerdo), II (3:3), III (4:4), IV (3:2), V (4:2), VI (2:3), VII (4:3), VIII (5:3), IX (3:4) e X (4:5). A distribuição assimétrica (2:4) e simétricas (1:1) e (5:5) não foram notadas. Medidas de comprimento e largura foram realizadas, observando-se média de 0,84 ± 0,23 mm para o comprimento e 0,55 ± 0,18 mm para a largura, além do cálculo da área total destas papilas por língua, que exibiram média de 2,74 ± 0,31 mm2 em machos e de 1,94 ± 0,14 mm2 em fêmeas. Não houve diferença significativa (p>0.05) quanto ao tipo de distribuição simétrica e assimétrica, quanto ao número de papilas valadas por língua e quanto ao número destas papilas por antímero. Entretanto, a média da área total destas papilas exibiu diferença estatisticamente significativa (p 0.05) quando comparados os sexos dos animais. Palavras-chave: Língua. Papilas valadas. Papilas gustatórias. References 1 SONNTAG, C. F. The comparative anatomy of the tongues of the mammalia - 1. General description of the tongue. Proceedings Zoological Society of London, v. 90, p. 115-129, 1920.13 BRUNI, A. C.; ZIMMERL, U. Anatomia degli animali domestici. 2. ed. Milano: Francesco Vallardi, 1950. p. 47. 2 DORAN, G. A. 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