Microstructure of Fu papillae
Cross-sections of Fu papillae with its 3D models from particular parts of studied ruminants tongues with its shape and structure are presented on Figures 1.1 – 6.3. Figure 7 presents 3D models of three types of Fu papillae CTCs in studied ruminants. Table 1 contains the estimated number and density of Fu papillae and taste buds. The height and diameter of Fu papillae are present in Table 2. Diameters of connective tissue cores (CTCs) of Fu papillae are in Table 3. The histomorphometry of stratified squamous epithelium on Fu papillae and the height of interpapillary stratified epithelium there is in Table 4.
Dorsal surface of the apex of the tongue
In cattle, Fu papillae were spread regularly between filiform papillae on the dorsal surface of the apex. The estimated number and density of Fu papillae reached 13 and 0.5 papilla per 1 cm2, respectively (Table 1). The Fu papillae were round in outline with convex and smooth surface and 1980.7 µm in height (Table 2, Fig. 1.1). In turn, the mean height of interpapillary stratified epithelium was 1567.3 µm, so the protrusion of Fu papillae amounted to 413.4 µm (Table 4, Fig. 8A). Approximated diameter of Fu papillae was 1070.2 µm (Table 2), whereas the mean diameters of CTC of these papillae reached 637.1 µm in the dorsal part, 358.9 µm in the medial part, and 1013.5 µm in the basal part. Thus, the shape of CTC was described as balloon-like (Table 3, Figs. 1.1, 7A, 8B). The height of stratified squamous epithelium on the dorsal part of Fu papillae and its keratinized layer was 115.4 µm and 17.9 µm, respectively (Table 4, Fig. 8C).
In European bison, Fu papillae were also spread evenly among filiform papillae on the dorsal surface of the apex with the number of 31 and density of 0.4 papilla/cm2 (Table 1).The Fu papillae were elliptical in outline with a convex and smooth dorsal surface (Fig. 1.2). The mean height of Fu papillae was approximately 1442.2 µm (Table 2). Considering an interpapillary stratified epithelium with 1051.7 µm in height, the protrusion of the papilla was 390.5 µm (Table 4, Fig. 8A). The Fu papillae were 953.8 µm in diameter (Table 2). Based on the diameters of its CTC in dorsal, medial, and basal part, which reached respectively 635.9 µm, 402.4 µm, and 715 µm balloon-like shape of CTC were distinguished (Table 3, Figs. 1.2, 7A, 8B). An approximate height of stratified squamous epithelium and its keratinized layer on the dorsal surface of Fu papillae was 140.8 µm, and 20.8 µm, respectively (Table 4, Fig. 8C).
The 222 evenly spread Fu papillae were observed on the dorsal surface of the Bison bonasus hybrid apex (Table 1). The approximated density of Fu papillae was nine papillae/cm2 (Table 1). Round in outline Fu papillae characterized by flat and smooth surface (Fig. 1.3). The calculated difference between the height of Fu papillae – 1326.2 µm, and the height of interpapillary stratified epithelium - 1166.2 µm equaled 160 µm, which was the value of the papillary protrusion (Tables 2, 4, Fig. 8A). The diameter of Fu papillae ranged between 554 µm and 722 µm, whereas the diameters of its CTC were 367.9 µm in dorsal part, 334.8 µm in the medial part, and 659.2 µm in the basal part (Tables 2, 3). These diameters indicated the columnar-like shape of Fu papillae CTCs (Figs. 1.3, 7B, 8B). The thickness of the stratified squamous epithelium on the Fu papillae was 119.7 µm, whereas its keratinized layer reached 19.2 µm (Table 4, Fig. 8C).
Ventral surface of the apex of the tongue
In cattle, 47 Fu papillae appeared symmetrically on lateral borders of the ventral surface of the tongue, while calculated density was around 7.8 papillae/cm2 (Table 1). Convex and smooth Fu papillae were round in outline (Fig. 2.1). The height of Fu papillae and interpapillary stratified epithelium was 1358.6 µm, and 1016 µm, respectively (Tables 2, 4). Thus, the average protrusion was 342.2 µm (Fig. 8A). The diameter of Fu papillae was 1056.2 µm (Table 2). However, dimensions of CTC in its dorsal part, medial part, and basal part reached approximately 923.8 µm, 620.1 µm, and 944.1 µm, respectively, and the balloon-like shape of CTC was described (Table 3, Figs. 2.1, 7A, 8B). The stratified squamous epithelium on the Fu papillae was 108.2 µm in thickness, while its keratinized layer amounted to 11.1 µm (Table 4, Fig. 8C).
In European bison, 50 Fu papillae covered both left and right marginal areas of the ventral surface of the tongue (Table 1). Calculated density was 2.6 papillae/cm2 (Table 1). The Fu papillae were elliptical or round in outline with a flat and smooth dorsal surface (Fig. 2.2) .Studied papillae were 1016.4 µm in height, while the interpapillary stratified epithelium reached 770.8 µm (Tables 2, 4). The approximate protrusion of these papillae equaled 245.6 µm (Fig. 8A). The estimated diameter of Fu papillae ranged between 552 µm and 1212 µm, whereas dimensions of CTC were 571.4 µm in dorsal part, 518.3 µm in medial part, and 802.5 µm in basal part, thus CTC had a columnar-like shape (Tables 2, 3, Figs. 2.2, 7B, 8B). The mean thickness of the stratified squamous epithelium and its keratinized layer on the Fu papillae was 139.5 µm, and 14.9 µm, respectively (Table 4, Fig. 8C).
In the total of 220 Fu papillae were arranged in a V-letter on the ventral surface of the Bison bonasus hybrid tongue (Table 1). Additionally, two types of Fu papillae were observed. Bigger Fu papillae created a border between smooth area and areas covered by lingual papillae, while smaller Fu papillae were spread between filiform papillae. Its density reached 20 Fu papillae/cm2 (Table 1). Fu papillae were elliptical or round in outline, while its dorsal surface was convex and smooth (Fig. 2.3). The height of Fu papillae, interpapillary stratified epithelium, and consequently the papillary protrusion reached 1104 µm, 930.1 µm, and 173.9 µm, respectively (Tables 2, 4, Fig. 8A). The Fu papillae diameter ranged between 490 µm and 844 µm, while the diameters of its CTC in dorsal, medial and basal part were 481.3 µm, 416.2, and 682.3 µm, respectively (Tables 2, 3, Fig. 8B). Thus, the shape of CTC was columnar-like (Figs. 2.1, 7B). The thickness of the stratified squamous epithelium on the Fu papillae was 96.9 µm, while its keratinized layer extends between 3 µm and 27 µm (Table 4, Fig. 8C).
Dorsal surface of the lingual body
In cattle and European bison, Fu papillae were observed on the lateral areas of the lingual body. In contrast, in the Bison bonasus hybrid Fu papillae were distributed on the whole dorsal surface of the lingual body.
In cattle observed 35 Fu papillae with the approximated density of 0.8 papilla/cm2 (Table 1). Round or elliptical Fu papillae in outline had convex and smooth dorsal surface (Fig. 3.1). The Fu papillae were 1343.9 µm in height, while an interpapillary stratified epithelium was 1096.9 µm in height, so the protrusion equaled 247 µm (Tables 2, 4, Fig. 8A). The diameter of Fu papillae was 1173.1 µm (Table 2). The diameters of CTC of Fu papillae were 700.4 µm in dorsal part, 484.6 µm in the medial part, and 1028.9 µm in the basal part, which resembled balloon-like shape (Table 3, Figs. 3.1, 7A, 8B). The stratified squamous epithelium was 122.3 µm in thickness, with 16.2 µm of the keratinized layer. (Table 4, Fig. 8C).
In European bison, the number and density of Fu papillae were 32 and 1 papilla/cm2, respectively (Table 1). The Fu papillae were round in outline with a convex and smooth dorsal surface (Fig. 3.2). The average height of these papillae and interpapillary stratified epithelium ranged between 1187 µm - 1438 µm, and 519 µm - 1372 µm, respectively (Tables 2, 4). Thus, the approximate protrusion of Fu papillae above the epithelium was 441.1 µm (Fig. 8A). The estimated diameter of Fu papillae reached 1102.5 µm, while CTC was columnar-like in shape with the mean dimensions – 476.5 µm in dorsal part, 451.9 µm in medial part, and 900.1 µm in basal part (Tables 2, 3, Figs. 3.2, 7B, 8B). The thickness of stratified squamous epithelium on Fu papillae was 166.5 µm, while keratinized layer – 20.6 µm (Table 4, Fig. 8C).
In the Bison bonasus hybrid calculated number and density of Fu papillae reached 118, and 3 Fu papillae/cm2, respectively (Table 1). Studied papillae were round in outline and had a flat and smooth dorsal surface (Fig. 3.3). Its average height ranged between 1269 µm and 1380 µm (Table 2). The height of the interpapillary stratified epithelium was 1221.5 µm. Thus the protrusion equaled 101.2 µm (Table 4, Fig. 8A). The Fu papillae were 828.9 µm in diameter, while the diameter of its CTC had in approximate 603.9 µm in the dorsal part, 462.4 µm in the medial part, and 768.5 µm in the basal part (Tables 2, 3, Fig. 8B). Thus, the shape of CTC was described as balloon-like (Figs. 3.3, 7A). Obtained average values of stratified squamous epithelium and its keratinized layer thickness on Fu papillae were 118.6 µm and 19 µm, respectively (Table 4, Fig. 8C).
Dorsal surface of the medial part of the torus
On the torus in cattle, European bison and Bison bonasus hybrid Fu papillae were observed on the medial and posterior part of the dorsal surface and on its lateral surfaces.
In cattle on the dorsal surface of the torus observed 15 Fu papillae, which estimated density was 0.5 papilla/cm2 (Table 1). In outline, Fu papillae were elliptical, whereas their dorsal surface was flat and smooth (Fig. 4.1). The height of Fu papillae and interpapillary stratified epithelium reached 1319.8 µm, and 1006.9 µm, respectively (Tables 2, 4). Furthermore, the protrusion of these papillae was 312.9 µm (Fig. 8A). The diameter of Fu papillae ranged between 1361 µm – 2155 µm, whereas diameters of CTC in dorsal, medial, and basal part were 1404.8 µm, 1698.1 µm and 1898.5 µm, respectively, which gave the cone-like shape of CTC (Tables 2, 3, Figs. 4.1, 7C, 8B). The thickness of stratified squamous epithelium on the Fu papillae was 143.2 µm, while its keratinized layer - 29.2 µm (Table 4, Fig. 8C).
In European bison, the number and density of pigmented Fu papillae were 23 and 0.8 papilla/cm2, respectively (Table 1). The dorsal surface of the elliptical in outline Fu papillae was convex and irregular (Fig. 4.2). The average height of Fu papillae and interpapillary stratified epithelium with an estimated value of papillary protrusion reached 1165.8 µm, 838.8 µm, and 327 µm, respectively (Tables 2, 4, Fig. 8A).The diameter of Fu papillae was 1628 µm (Table 2). In turn, the diameter of CTC in dorsal, medial and basal part amounted to 818.1 µm, 929.3 µm, and 1402.3 µm, respectively, which gave the cone-like shape of CTC (Table 3, Figs. 4.2, 7C, 8B). The thickness of the stratified squamous epithelium and its keratinized layer on Fu papillae was 150.6 µm, and 37.1 µm, respectively (Table 4, Fig. 8C).
The number and density of Fu papillae on the dorsal surface of the torus in the Bison bonasus hybrid reached 15 and 0.6 papilla/cm2, respectively (Table 1). Fu papillae were round in outline, while its dorsal surface was flat and smooth (Fig. 4.3). The Fu papillae were 2060.1 µm in height, while the height on the interpapillary stratified epithelium ranged between 1612 µm and 2148µm (Tables 2, 4). Thus, the protrusion of the papillae above the epithelium equaled 162.3 µm (Fig. 8A). The diameter of Fu papillae was 1357.7 µm, while the dorsal, medial and, a basal diameter of CTC reached 997.3 µm, 687.6 µm, and 1277.9 µm, respectively (Tables 2, 3, Fig. 8B). Thus, the connective tissue core was balloon-like in shape (Figs. 4.3, 7A). The thickness of stratified squamous epithelium on the Fu papillae was 121.9 µm, while its keratinized layer reached 35.8 µm (Table 4, Fig. 8C).
Dorsal surface of the posterior part of the torus
On the posterior part of cattles’ torus observed 30 Fu papillae, with a density of 0.9 papillae/cm2 (Table 1). Round in outline, Fu papillae had a convex and smooth dorsal surface (Fig. 5.1). The height of Fu papillae and interpapillary stratified epithelium was 1402.1 µm and 470 µm, respectively (Table 2, 4). Therefore, the protrusion of these papillae equaled 932.1 µm (Fig. 8A). The Fu papillae were 1095.7 µm in diameter (Table 2). The approximate dimensions of CTC in dorsal, medial, and basal parts amounted to 881.9 µm, 649.9 µm, and 1265.8 µm, which gives a balloon-like shape of CTC (Table 3, Figs. 5.1, 7A, 8B). The average thickness of the stratified squamous epithelium and its keratinized layer on the Fu papillae ranged between 47 µm – 193 µm and 6 µm – 39 µm, respectively (Table 4, Fig. 8C).
Like cattle, the estimated density of Fu papillae in European bison was 0.9 papilla/cm2, but the number of Fu papillae equaled 20 (Table 1). The dorsal part of rounded or elliptical in outline Fu papillae was also convex and smooth (Fig. 5.2). The average values of papilla height, the height of interpapillary stratified epithelium, and the protrusion of papillae above the epithelium reached 1397.4 µm, 680.7 µm, and 706.7 µm, respectively (Tables 2, 4, Fig. 8A). The diameter of Fu papillae ranged between 1134 µm - 1883 µm, while the columnar-like shape of CTC was characterized by diameters – 1439.4 µm in dorsal part, 1456.2 µm in medial part, and 1769.2 µm in the basal part (Tables 2, 3, Figs. 5.2, 7B, 8B). The stratified squamous epithelium was 129.5 µm in height, while its keratinized layer reached 19.2 µm (Table 4, Fig. 8C).
The calculated number and density of Fu papillae in the Bison bonasus hybrid was 46 and 2.7 papillae / cm2, respectively (Table 1). The papillae were round in outline with the convex and smooth dorsal surface (Fig. 5.3). The height of studied papillae ranged between 1032 µm - 1425 µm, while the height of interpapillary stratified epithelium was 944.4 µm, so the protrusion of the papilla above the epithelium equaled 277.1 µm (Tables 2, 4, Fig. 8A). The diameter of Fu papillae amounted to 895 µm (Table 2). In turn, CTC had a balloon-like shape, with an approximate diameter – 662.2 µm in dorsal part, 558.1 µm in medial part, and 1067.4 µm in the basal part (Table 3, Figs. 5.3, 7A, 8B). Furthermore, the height of stratified squamous epithelium with its keratinized layer was 113.3 µm, and 16.8 µm, respectively (Table 4, Fig. 8C).
Lateral surfaces of the torus
The 45 Fu papillae with a density of 0.9 papilla/cm2 were regularly distributed on the lateral surfaces of cattle torus (Table 1). The Fu papillae were round in outline with a convex and smooth dorsal surface (Fig. 6.1). It reached a height of 1314 µm, while the height of interpapillary stratified epithelium ranged between 864 µm – 1577 µm (Tables 2,4). Therefore, the papillary protrusion was 108.7 µm (Fig. 8A). The Fu papillae were 1071.7 µm in diameter, while the CTC was cone-like in shape, and measured 574.6 µm in dorsal part, 633.2 µm in medial part, and 1056.6 µm in basal part (Tables 2, 3, Figs. 6.1, 7D, 8B). The thickness of stratified squamous epithelium on Fu papillae amounted to 147.1 µm, whereas the thickness of its keratinized layer was 31.5 µm (Table 4, Fig. 8C).
In European bison approximated number of Fu papillae on the left and right surface of torus was 46, while the density reached 1.1 papilla/cm2 (Table 1). The dorsal part of the elliptical in outline Fu papillae was convex and smooth (Fig. 6.2). The heights of Fu papillae and interpapillary stratified epithelium ranged between 1103 µm - 1717 µm, and 864 µm – 1423 µm, respectively (Tables 2, 4). Thus, the estimated protrusion of Fu papillae above the epithelium was 441.2 µm (Fig. 8A).The diameter of Fu papillae reached 655.6 µm (Table 2). In turn, the columnar-like shape of CTC was characterized by dimensions – 381.8 µm in dorsal part, 389.8 µm in medial part, and 665.9 µm in basal part (Table 3, Figs. 6.2, 7B, 8B). The thickness of stratified squamous epithelium on Fu papillae with its keratinized later was 1020.9 µm, and 20.9 µm, respectively (Table 4, Fig. 8C).
The Bison bonasus hybrid total number of Fu papillae was 38, while the density reached 1.06 papilla/cm2 (Table 1). Round or elliptical in outline Fu papillae with flat and smooth dorsal surface were 1601.9 µm in height (Table 2, Fig. 6.3). Furthermore, the height of the interpapillary stratified epithelium was 1408.9 µm, so the protrusion of the papilla was 193 µm (Table 4, Fig. 8A). The Fu papillae were 964 µm in medial diameter, while CTC reached 708.9 µm in dorsal part, 570.6 µm in medial part, and 1063.7 µm in basal part, which gave the balloon-like shape of CTC (Tables 2, 3, Figs. 6.3, 7A, 8B). The thickness of the stratified squamous epithelium and its keratinized layer on Fu papillae approximate 121.2 µm, and 17.7 µm, respectively (Table 4, Fig. 8C).
Taste buds
Dorsal surface of the apex of the tongue
Three-dimensional models of Fu papillae presented variations in the arrangement of taste buds on the dorsal surface of Fu papillae in cattle, European bison, and Bison bonasus hybrid shown in Figure 1.
In cattle, three 3D models of Fu papillae showed three different patterns of distribution of taste buds. On the one hand, taste buds were arranged in the median part of the papilla in the form of strips located perpendicularly to the median line of the tongue (Fig. 1.1a). On the other hand, taste buds formed clusters centrally or on the left side of Fu papillae (Figs. 1.1b, 1.1c). The average number of taste buds was 23 (Table 1). Furthermore, the estimated density reached 20 taste buds/mm2 (Table 1). Moreover, the average diameter of taste buds ranged between 29.9 µm – 62.9 µm (Table 5).
The 3D models of Fu papillae in European bison presented 12 taste buds in average arranged in clusters on the right or left part of the papilla (Table 1, Figs. 1.2a, 1.2b). The density of taste buds on the dorsal surface of Fu papillae was 12 taste buds/mm2 (Table 1), while the mean diameter of taste buds reached approximately 47.9 µm (Table 5).
In Bison bonasus hybrid, three 3D models of Fu papillae were prepared (Figs. 1.3a, 1.3b, 1.3c). In two 3D models of these papillae, a single taste bud arranged centrally was observed (Figs. 1.3a, 1.3c). In turn, in the third one observed a lack of taste buds (Fig. 1.3b). The calculated density of taste buds in these Fu papillae was three taste buds/mm2(Table 1). Furthermore, the mean diameter of taste buds was 32.5 µm (Table 5).
Ventral surface of the apex of the tongue
The three-dimensional reconstructions of Fu papillae on the ventral surface of the tongue in studied species of ruminants are present in Figure 2.
In cattle, the 64 taste buds, on average, were evenly arranged posteriorly or on the whole surface of the dorsal part of Fu papillae (Table 1, Figs. 2.1a, 2.1b). The density of taste buds in these papillae reached 41 taste buds/mm2, while the diameter of taste buds was 39.5 µm (Tables 1, 5).
In European bison, taste buds were arranged anteriorly and near the right border of the dorsal surface of Fu papillae (Figs. 2.2a, 2.2b). The average number of taste buds from two 3D models was 18 taste buds, while their estimated density reached 20 taste buds/mm2 (Table 1). The average diameter of taste buds was approximately 41.7 µm (Table 5).
The patterns of 20 taste buds in average in Bison bonasus hybrid were arranged posteriorly in a crescent shape and on the right part of the dorsal surface of Fu papillae (Table 1, Figs. 2.3a, 2.3b). The estimated density of taste buds was 21 taste buds/ mm2 (Table 1). In turn, their mean diameter reached 42.6 µm (Table 5).
Dorsal surface of the lingual body
The 3D reconstructions of Fu papillae on the lingual body with the arrangement of taste buds are in Figure 3.
The taste buds observed on 3D models of Fu papillae in cattle formed perpendicular or parallel strips concerning the median line of the tongue (Figs. 3.1a, 3.1b, 3.1c). Averaged number of taste buds was 41, while its estimated density reached 22 taste buds/mm2 (Table 1). In turn, the measured diameter of taste buds ranged between 30.2 µm – 55.6 µm(Table 5).
In European bison, the arrangement of taste buds on the dorsal surface of the Fu papillae was different in each of the reconstructed papillae. On the first one, taste buds were arranged posteriorly in a crescent shape (Fig. 3.2a). On the second one, taste buds formed a centrally located strip arranged perpendicularly to the median line of the tongue (Fig. 3.2b). In turn, on the third one, a group of taste buds was located on the left part of the dorsal surface of Fu papilla (Fig 3.2c). The average number of taste buds from these three models equals 10, as same as the estimated density - 10 taste buds/mm2 (Table 1). Moreover, the measured diameter of taste buds was 42.4 µm (Table 5).
In the Bison bonasus hybrid, two 3D models of Fu papillae had centrally arranged taste buds (Figs. 3.3a, 3.3b). The mean number of taste buds reached 3, while their density was five taste buds/mm2(Table 1). Measured and averaged diameter of taste buds approximate 45.2 µm (Table 5).
Dorsal surface of the medial part of the torus
The reconstructions of Fu papillae on the dorsal surface of the torus are presented in Figure 4.
Around 13 taste buds formed clusters arranged posteriorly or centrally on the dorsal surface of Fu papillae in cattle (Figs. 4.1a, 4.1b). The density of these taste buds reached five taste buds/mm2, while the diameter of these taste buds was 41.1 µm (Tables 1, 5).
In European bison 4, taste buds were arranged on the left or central part of the dorsal surface of Fu papillae (Table 1, Figs. 4.2a, 4.2b). The estimated density of taste buds was two taste buds/mm2, whereas its mean diameter equaled 45.1 µm (Tables 1, 5).
In Bison bonasus hybrid on two 3D models of Fu papillae, 13 taste buds arranged anteriorly were observed (Table 1, Figs. 4.3a, 4.3b, 12). The density of taste buds approximately 11 taste buds/mm2, whereas its diameter, reached 42.2 µm (Table 1, 5, Fig. 13).
Dorsal surface of the posterior part of the torus
Reconstructions of Fu papillae from the posterior surface of the torus shown in Figure 5.
The average number of 37 taste buds evenly spread on the dorsal surface of the Fu papillae in cattle present in Table 1, and Figs. 5.1a, 5.1b. Its estimated density reached 24 taste buds/mm2, while its mean diameter ranged between 30.1 µm – 49.4 µm (Tables 1, 5).
In European bison observed 14 taste buds on average were spread unevenly on the anterior, posterior, and lateral parts of the Fu papillae, creating small clusters (Table 1, Figs. 5.2a, 5.2b). The density of taste buds was four taste buds/mm2, while its mean diameter reached 42.9 µm (Tables 1, 5).
Around 13 taste buds formed vertical and circular clusters on the dorsal surface of Fu papillae in the Bison bonasus hybrid (Table 1, Figs. 5.3a, 5.3b). The estimated density of these taste buds is 11 taste buds/mm2, whereas its diameter was 36.5 µm (Tables 1, 5).
Lateral surfaces of the torus
The 3D models of Fu papillae from lateral surfaces of the torus are presented in Figure 6.
In cattle, 17 taste buds were arranged centrally and on the left side of the dorsal surface of Fu papillae (Table 1, Figs. 6.1a, 6.1b). The density of taste buds in Fu papillae reached 16 taste buds/mm2 in average (Table 1). Furthermore, the mean diameter of taste buds amounted to 44.8 µm (Tab. 5).
On two reconstructions of Fu papillae in European bison clusters of 14 in average taste buds were observed on the left side and the posterior part of Fu papilla (Table 1, Figs. 6.2a, 6.2b). The density of these taste buds equaled 18 taste buds/mm2 (Table 1). Additionally, the measured diameter of taste buds ranged between 23.8 µm – 56.1 µm (Table 5).
In the Bison bonasus hybrid, taste buds were arranged posteriorly or centrally, close to the left area of the dorsal surface of Fu papillae (Figs. 6.3a, 6.3b). Approximately 23 taste buds were observed, while its estimated density reached 19 taste buds/mm2 (Table 1). Moreover, the mean diameter of those taste buds was 36.9 µm (Table 5).