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Angioarchitectural structure and functional distributive pattern of the filiform papillae on the meso-dorsal surface of the rabbit tongue
= = = = = = = = = = ANNALS Of ANATOMY
Angioarchitectural structure and functional distributive pattern of the filiform papillae on the meso-dorsal surface of the rabbit tongue Koei Ojima D ental Research Institute, School of D ent istry at Toky o, Th e Ni ppon Dent al Unive rsity, 1-9-20, Fujimi, Chiyo da-ku, Tok yo, 102-R1 59, Jap an
Summary. The angioarchit ectural classification and distributive patterns were investigated in the filiform papill ae (FiP ) on the meso-dor sa l surface of the rabbit tongue by using micro vascular cast specime ns (MV CS) and the scanning ele ctron microscop e (SE M) . Th e author exa mined the micr ovascular network struc tures, which consisted of ascending and descend ing branches ente ring the FiP. Th ey inclin ed in a posteri or (pharynx) dir ection , and dense ly and geome trically covered the meso-dor sal surface, directing the spoo n-like concave face in an ant erior direction . FiPs could be classified into three types: a small filiform papill a (SfP) cove ring on the meso-dorsal surface except for th e mar ginal part of the intermolar eminen ce (MIME) and the inte rmo lar emine nce itself (IME): a spoon-like concave structure facing in an anterior (apex) dir ection with an arro whea d-like top: a middl e filiform papill a (MfP) on the MIM E , made up of a long tri anglelike concave structure with a sharp arrowhead-like top and inclined at right angles to the IME. A large filiform papilla (UP) on the whole swelling dorsal ar ea of the IM E was formed by a long triangle-like con cave structure with a sharper arrowhead-l ike top. UPs are longer and lar ger than MfP s and inclined toward s the phar ynx.
FiPs, con sistm g of the asce nding and desc ending bra nches, were espec ially int er esting from the point of view of their morph ological fea t ures, dist ribution and function. After initi al refer en ce to an atl as of rabbit anatomy (Ba ro ne 1973), fur ther study of the structural and thr ee-dimen sion al morphological features of th e lingual papill ae on the dorsal surface of the rabbit tongue was don e in detail by SEM (Chamoro et aJ. 1987; Iwasaki 1987; Kobayashi et al. 1989; Ko bayashi 1992; Ojima et a1. 1996: Shimamura et aJ. 1972; Toyoh ashi et al. 1981) . A corrosi on castin g meth od was employed to reveal the microvascul ar structure of FiPs (Ojima and Lowe 1995; Ojima et aJ. 1996 a, b; Ojima et aJ. 1997 a, b) , but as far as the author kn ows, this is the first appli cati on of the fine morphological classificat ion of FiPs in the meso-d orsal region. Little is known, however , of studies on the relati on ships between the morpholo gical characteristics, classifica tory differences and distributive patterns in FiPs on the meso-dorsal surface of the rabbit tongue. The purpose of the present study is to deal with this relationship on MV CS of FiPs on the meso-d orsal surface, except for the MIME and IME, the MIME and the whole are a of IME , by SEM in detail.
Key words: Rabbit ton gue - Filiform papill ae - Microvascular cast spec ime ns - SEM
Material and methods Introduction FiPs play a me chanical ro le, tha t is, mastication, transporting wate r and the food mass toward s the pharyn x. Th e specific featur es of the micro vascular netw ork of Correspondence to : K. Oj irna
Ann Anat (1998) 180: 547-553 © Gustav Fischer Verl ag
Tongue s from 65 ra bb its. Oryctolagus cuniculus, were obtaine d fro m a comme rcial supplie r and used in thi s study. All th e rabbits were adults of un kn own age. wcighing between 2.0 and 3.5 kg, and both sexes (55 fe ma les and 10 males) we re repre se nted. Th e anima ls wer e anaesthetized with an ove rdose of Nem butal so dium solution (Pentob arbital so dium inje ction) and killed. Th eir tongues wer e th en remove d and both lingual art er ies wer e
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Fig. 1. A schematic diagram showing the distribution of the various types of lingual papillae on the antero-posterior dorsal surface of the rabbit tongue. The tongues were divided into three regions: the anterior (A-zone), middle (or intermolar eminence: IME), narrower and higher than A-zone (B-zone), and the posterior region (C-lOne). In these three regions, six types of lingual papillae could be distinguished: the small filiform papillae (SfP) (0) on the antero-posterior dorsal surface, except for the IME and the marginal part of IME (MIME) , the fungiform papillae (FuP) (@) on the anterior part, the middle filiform papillae (MfP) (e) on the anterior and both peripheral marginal parts of the IME , the large filiform papillae (LfP) (e) on the IME, a pair of foliate papillae (FoP) (~) located on both the postero-peripheral parts and a pair of circumvallate papillae (CvP) (@) located behind the FoP and near the midline symmetrically. A relatively small number of FuP (approximately 24) were spora dically, consistently and almost uniformly scattered among the numerous SiPs.
III E : largio of Intenolar eaiDcoce SfP
SuI I filifora papillae
U P
l i dd l e filifor a papillae
UP
Large f iIi for a papillae
Scale bar
500 /L a
548
Fig. 3. Upper view of the composite photograph corresponding to the square insets of A-C in Fig. 2. In Figs. A and B, SfP on the meso-dorsal surface, MfP on the MIME, and UP on the 1ME are shown as well as in Fig. C on the IME .
...
Fig. 2. Upper view of a composite photograph of one of the scanning electron photomicrographs with low magnification of MVCS of the meso-dorsal surface of the rabbit tongue corresponding to the square inset of B-zone in Fig. 1.
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cannulated and prepared for macroscopic, stereomicroscopic and SEM observation. For SEM observations, each tongue was rinsed with 0.9% physiological saline solution or Ringer's solution at 35-37°C. Vascular perfusion with 0.9% physiological saline solution or Ringer's solution was then carried out until the lingual veins were refilled by the solution, and 5% glutaraldehyde solution in phosphate buffer (pH 7.4) was injected into
Fig. 4. Upper view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of SfPs whose concave network-like face pointed in an anterior direction, consisting of the ascending and descending capillary branches and composed of geometrically regular microvascular structures.
both the lingual arteries for fixation of the vessels and their tributaries. Both lingual arteries were filled with synthetic resin (Mercox CL-2R 5, CL-2B 5, CL-2C 5, Dainippon lnki Chemical Co., Ltd. Tokyo, Japan) under manual pressure and the injected specimens were fixed for 0.3 hrs at room temperature and kept for 0.3 hrs at 55°C in an incubator. The specimens were then polymerized completely, and im-
Fig.5. Anterior view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of SfPs the concave network-like face of which consists of microvascular structures. They are arranged geometrically and regularly.
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mersed in 20% KOH or NaOH solution for over 3 hrs at room temperature until the surrounding soft tissues were dissolved. The finest macerated vascular samples were carefully washed 23 times with running distilled warm tap water at 45-50°C and gently dried for 2-3 days at 55°C in an incubator. The MVCS of the whole tongue were mounted on specimen stubs, and coated by platinum sputtering. The specimens were then examined with a S-4000 scanning electron microscope (HITACHI, Tokyo, Japan) at an accelerating voltage of 5 kV.
MfPs . The LfPs are wider and longer than the MfPs. LfPs form a long triangle-like concave structure with a sharper arrowhead-like top facing in an anterior direction and inclined in a posterior direction (pharynx). They cover the whole swelling dorsal area of the IME (Fig. 2, Fig. 3 A-C, Fig. 7 A-C).
Results Macroscopically, the rabbit tongue is relatively narrow and long (in the adult approximately 7.0 em long, 2.5 em wide and 1.0 em deep), running from the apex (anterior) in the direction of the root (posterior) with a rounded tip in front. It is composed of three regions, the anterior (Fig. 1, A-zone), middle or intermolar eminence (IME) (Fig. 1, B-zone) and the posterior region (Fig. 1, C-zone) on the dorsal surface of the lingual body. In the middle dorsal surface region, the !ME (Fig. 1) is located longitudinally and forms a long arrowhead-like swelling from the center towards the pharynx. Six kinds of lingual papillae were observed, the small filiform papillae (SfP) (Fig. 1, Fig. 2, and Fig. 3 A and B) and fungiform papillae (FuP) in the anterior region, except for the IME and their marginal parts, the middle filiform papillae (MfP) (Fig. 1, Fig. 2 and Fig. 3 A and B) on the marginal part of IME (MIME) (Fig. 2), the large filiform papillae (LfP) (Fig. 1, Fig. 2 and Fig. 3 A-C) on whole area of the IME (Fig. 2), the foliate papillae (FoP) on both the posteroperipheral sides and circumvallate papillae (CvP) located behind the FoP on both sides posteriorly. FoPs and CvPs are located symmetrically on both sides of the midline (Fig. 1). In the present study, the microvascular morphological characteristics and pattern of distribution were investigated by means of MVCS of SfPs, MfPs and LfPs, composed primarily of the ascending and descending capillary branches, on the meso-dorsal surface (B-zone) of the rabbit tongue with th e SEM in detail (Figs. 2, 3). SfPs covered all the meso-dorsal surface, except for the IME and MIME, and faced their concave aspect, consisting of a spoon-like network structure, in an anterior direction. Their arrowhead-like tips inclined in a posterior direction geometrically and regularly (Fig. 2, Fig. 3 A and B, Fig. 4 A-C, Fig. 5 A-C). The outer frame of MfPs consists of the ascending and descending branches and the y are slimmer and longer than the SfPs. Their long triangle-like concave network structures, the tops of which are sharper than th at of SfPS, faced in an anterior direction. MfPs surround both the peripheral and anterior parts of the margin of IME and are at right angles to the swelling IME (Fig. 2, Fig. 3 A and B, Fig. 6 A-C). The outer frame of the LfPS forms the ascending and descending capillary branches as well as those of SfPs and
Fig. 6. Anterior view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of MfPs the outer frame of which consisted of ascending and descending capillary branches which are slimmer and longer than SfP. Their long triangle-like concave network microvascular structures are in an arrowhead-like shape the top of which is sharper than that of SfPsfacing in an anterior direction.
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Discussion Although many ultrastructural morphological studies have been done on the lingual papillae of the rabbit tongue, relatively few have dealt with the microvascular structure and functional classification of FiP on the mesodorsal surface of the tongue. The purpose of this study was to undertake a detailed SEM three-dimensional observation of the morphological characteristics of MVCS of FiP on the meso-dorsal surface of the rabbit tongue. This is composed of the dorsal surface, the MIME and IME, and classified SfP on the dorsal surface, except for the MIME and IME, MfP on the MIME and LfP on the IME. As described by Hellekant (1971), the blood supply to the tongue is more plentiful than that of most other tissues, and it may be reasonable to suppose that the blood vessels inside the lingual papillae of the tongue form its basic structural core. The MVCS methods applied in this study (Ojima et al. 1997a-e) provided a relatively practical and useful observational method for studying the three-dimensional architecture of the microvascular network structure of FiP (SfP, MfP and LfP) of the rabbit tongue. The author could observe MVCS of FiP under better specimen conditions and obtained good photomicrographs with the SEM. There are no comparative descriptions entering into details of the classificatory relationships between the angioarchitectural structure and functional distributive pattern in the reference book on the rabbit (Borone et al. 1973). The tongue of the rat in the SEM (Stereoscan) (Svejda and Skach 1971), differentiation of lingual filiform papillae of the rat on organ culture (1973), morphogenesis of the rat lingual filiform papillae (Bratze and Farbman 1975), three-dimensional and surface structures of rat filiform papillae (Iida et al. 1985), morphological studies of rat lingual filiform papillae (Nagato et al. 1989), a developmental map of the connective tissue core and microvasculature of the filiform papillae (Okada et al. 1994), a microvascular structural study of the filiform papillae in the cat tongue (Ojima and Lowe 1995), and the distributive pattern, form and function seen in microvascular cast specimens of filiform papillae on the anterodorsal surface of the adult rat tongue (Ojima et al. 1996c) have all been carried out. Also comparative studies of the dorsal surface of the Fig. 7. Anterior view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of tongue in three mammalian species by SEM (Iwasaki et UPs which are wider and longer than those of MfPs. Their long al. 1987), comparative studies on the stereo-architecture triangle-like concave network microvascular structure faces in an of the connective tissue papillae in some mammalian tonanterior direction and the arrowhead-like shape, the top of gues (Kobayashi and Iwasaki 1988) and angioarchitecturwhich is sharper and longer than that of MfPs, is inclined in a al comparison of the filiform papillae of the cat and posterior direction (pharynx). rabbit using scanning electron microvascular specimens Scale bar in Figs. 3A-C-7 A-C =100 urn, The arrows at the (Ojima et al. 1996b) have also been done. upper and lower parts and at right and left in Figs. 1 and 2 and The present study was carried out to obtain further inFigs. 3 A-C-7 A-C indicate the anteriordirection. formation on the three kinds of FiP: SfP, MfP and LiP. On the basis of the results, from the morphological characteristics of MVCS of FiP observed by means of the
552
SEM, PiP can be classified into three kinds: SiP on the Ojima K, Lowe AA (1995) Microvascular structural study of the filiform papillae in the cat tongue. Shigaku (Odontology) 82: meso-dorsal surface, except for the MIME and IME, MiP 1325-1336 on the MIME and LiP on the IME according to the size, shape and directional pattern. Each FiP aspect is com- Ojima K, Takeda M, Saiki C, Matsumoto S (1996 a) Functional and morphological observations on the microvascular strucposed of the ascending and descending capillary l?ops, i~ ture of the filiform and fungiform papillae in the cat tongue. clined in a posterior direction (pharynx) and with their Ann Anat 178: 361-364 concave face pointed in an anterior direction. Ojima K, Takeda M, Saiki C, Matsumoto S (1996 b) AngioarchiSfP, MiP and LiP playa mechanical role, that is, mastitectural comparison of the filiform papillae of the cat and rabcation and transporting water and the masticated food bit using scanning electron microscopic specimens. Ann Anat 178: 449--454 mass towards the pharynx in cooperation with each other Ojima K, Saiki C, Matsumoto S, Takeda M (1996 c) The distribuon the meso-dorsal surface of the rabbit tongue.
References Borone R, Pavaux C, Blin PC, Cuq P (1973) Atlas D' Anatomie du Lapin. Masson & Edutiturs, Paris, pp 75-78 Baratz RS, Farbman AI (1975) Morphogenesis of rat lingual filiform papillae. Am J Anat 143: 283-302 Chamoro CA, Sandoval J, Fernandez JG, Fernandez M, de Paz P (1987) Comparative study of the lingual papillae of cats (Felis catus) and rabbits (Oryctolagus cuniculus) using the scanning electronic microscope. Anat Histol Embryo 16: 37--47 Farbman AM (1973) Differentiation of lingual filiform papillae of the rat in organ culture. Arch Oral Biol 18: 197-202 Hellekant G (1971) Circulation of the tongue. In: Emmelin N, Zotterman Y (Eds) Oral Physiology. Pergamon Press, Oxford, pp 127-137 Iida M, Yoshioka I, Muto R (1985) Three-dimensional and surface structures of rat filiform papillae. Acta Anat 21: 237-244 Iwasaki S (1987) Morphological studies of the lingual mucosa of the rabbit. Fine structure of the mucosal epithelium. Shigaku (Odontology) 74: 1235-1264 Iwasaki S, Miyata T, Kobayashi K (1987) Comparative studies of the dorsal surface of the tongue in three mammalian species by scanning electron microscopy. Acta Anat 128: 140-146 Kobayashi K, Iwasaki S (1988) Comparative studies on the stereo architecture of the connective tissue papillae in some mammalian tongues. Prog Clin BioI Res 259: 303-308 Kobayashi K, Asami T, Kitajima K, Takahashi K, Iwasaki S (1989) Stereo structure of the connective tissue papillae of the rabbit tongue. Acta Anat Nippon 64: 224-232 Kobayashi K (1992) Comparative anatomical studies on the tongues with special reference to the connective tissue cores of the lingual papillae. Shigaku (Odontology) 80: 661-678 Nagoto T, Nagaki M, Murakami M, Tanioka R (1989) Morphological studies of rat lingual filiform papillae. Okajima Folia Anat Jpn 66: 195-210
tive pattern, form and function seen in microvascular cast specimens of filiform papillae on the anterodorsal surface of the adult rat tongue. Ann Anat 178: 531-535 Ojima K, Takeda M, Saiki C, Takahashi T, Matsumoto S (1997 a) A-form distribution seen in microvascular cast specimens of the filiform and fungiform papillae on the anterior central dorsal surface of the cat tongue. Ann Anat 179: 201-208 Ojima K, Takahashi T, Takeda M, Matsumoto S, Saiki C (1997 b) Angioarchitectural comparison of the fungiform papillae of the cat and rabbit using scanning electron microscopic specimens. Ann Anat 179: 209-214 Ojima K, Takeda M, Matsumoto S, Saiki C, Takahashi T (1997 c) Functional role of V form distribution seen in microvascular cast specimens of the filiform and fungiform papillae on the posterior central dorsal surface of the cat tongue. Ann Anat 179: 321-327
Ojima K, Matsumoto S, Saiki C, Takahashi T, Takeda M, Mitsuhashi F (1997 d) Angioarchitectural structure of the fungiform papillae on the anterodorsal surface of the rabbit tongue. Ann Anat 179: 329-333 Ojima K, Takeda M, Matsumoto S, Nakanishi I (1997 e) Microvascular fin-like structure of the foliate papillae of the rabbit tongue using scanning electron microscopic specimens. Ann Anat 179: 511-515 Okada S, Ohta M, Yoshida S (1994) Developmental map of the connective tissue core and microvasculature of the filiform papillae. Dentistry 31: 9-16 Shimamura A, Tokunaga J, Toh R (1972) Scanning electron microscopic observation on the taste pores and taste hairs in rabbit gustatory papillae. Arch Histol Jap 34: 51-60 Svejda J, Skach M (1971) Die Zunge der Ratte im Raster-Elektronenmikroskop (Stereoscan). Z mikrosk anat Forsch 84: 101-116
Toyoshima K, Shimamura A (1982) Scanning electron microscope study of the epithelium-connective tissue interfaces of the tongue pepillae in the rat. Jpn J Oral Biol 24: 1019-1022 Accepted June 10, 1998
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Angioarchitectural structure and functional distributive pattern of the filiform papillae on the meso-dorsal surface of the rabbit tongue Koei Ojima D ental Research Institute, School of D ent istry at Toky o, Th e Ni ppon Dent al Unive rsity, 1-9-20, Fujimi, Chiyo da-ku, Tok yo, 102-R1 59, Jap an
Summary. The angioarchit ectural classification and distributive patterns were investigated in the filiform papill ae (FiP ) on the meso-dor sa l surface of the rabbit tongue by using micro vascular cast specime ns (MV CS) and the scanning ele ctron microscop e (SE M) . Th e author exa mined the micr ovascular network struc tures, which consisted of ascending and descend ing branches ente ring the FiP. Th ey inclin ed in a posteri or (pharynx) dir ection , and dense ly and geome trically covered the meso-dor sal surface, directing the spoo n-like concave face in an ant erior direction . FiPs could be classified into three types: a small filiform papill a (SfP) cove ring on the meso-dorsal surface except for th e mar ginal part of the intermolar eminen ce (MIME) and the inte rmo lar emine nce itself (IME): a spoon-like concave structure facing in an anterior (apex) dir ection with an arro whea d-like top: a middl e filiform papill a (MfP) on the MIM E , made up of a long tri anglelike concave structure with a sharp arrowhead-like top and inclined at right angles to the IME. A large filiform papilla (UP) on the whole swelling dorsal ar ea of the IM E was formed by a long triangle-like con cave structure with a sharper arrowhead-l ike top. UPs are longer and lar ger than MfP s and inclined toward s the phar ynx.
FiPs, con sistm g of the asce nding and desc ending bra nches, were espec ially int er esting from the point of view of their morph ological fea t ures, dist ribution and function. After initi al refer en ce to an atl as of rabbit anatomy (Ba ro ne 1973), fur ther study of the structural and thr ee-dimen sion al morphological features of th e lingual papill ae on the dorsal surface of the rabbit tongue was don e in detail by SEM (Chamoro et aJ. 1987; Iwasaki 1987; Kobayashi et al. 1989; Ko bayashi 1992; Ojima et a1. 1996: Shimamura et aJ. 1972; Toyoh ashi et al. 1981) . A corrosi on castin g meth od was employed to reveal the microvascul ar structure of FiPs (Ojima and Lowe 1995; Ojima et aJ. 1996 a, b; Ojima et aJ. 1997 a, b) , but as far as the author kn ows, this is the first appli cati on of the fine morphological classificat ion of FiPs in the meso-d orsal region. Little is known, however , of studies on the relati on ships between the morpholo gical characteristics, classifica tory differences and distributive patterns in FiPs on the meso-dorsal surface of the rabbit tongue. The purpose of the present study is to deal with this relationship on MV CS of FiPs on the meso-d orsal surface, except for the MIME and IME, the MIME and the whole are a of IME , by SEM in detail.
Key words: Rabbit ton gue - Filiform papill ae - Microvascular cast spec ime ns - SEM
Material and methods Introduction FiPs play a me chanical ro le, tha t is, mastication, transporting wate r and the food mass toward s the pharyn x. Th e specific featur es of the micro vascular netw ork of Correspondence to : K. Oj irna
Ann Anat (1998) 180: 547-553 © Gustav Fischer Verl ag
Tongue s from 65 ra bb its. Oryctolagus cuniculus, were obtaine d fro m a comme rcial supplie r and used in thi s study. All th e rabbits were adults of un kn own age. wcighing between 2.0 and 3.5 kg, and both sexes (55 fe ma les and 10 males) we re repre se nted. Th e anima ls wer e anaesthetized with an ove rdose of Nem butal so dium solution (Pentob arbital so dium inje ction) and killed. Th eir tongues wer e th en remove d and both lingual art er ies wer e
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Fig. 1. A schematic diagram showing the distribution of the various types of lingual papillae on the antero-posterior dorsal surface of the rabbit tongue. The tongues were divided into three regions: the anterior (A-zone), middle (or intermolar eminence: IME), narrower and higher than A-zone (B-zone), and the posterior region (C-lOne). In these three regions, six types of lingual papillae could be distinguished: the small filiform papillae (SfP) (0) on the antero-posterior dorsal surface, except for the IME and the marginal part of IME (MIME) , the fungiform papillae (FuP) (@) on the anterior part, the middle filiform papillae (MfP) (e) on the anterior and both peripheral marginal parts of the IME , the large filiform papillae (LfP) (e) on the IME, a pair of foliate papillae (FoP) (~) located on both the postero-peripheral parts and a pair of circumvallate papillae (CvP) (@) located behind the FoP and near the midline symmetrically. A relatively small number of FuP (approximately 24) were spora dically, consistently and almost uniformly scattered among the numerous SiPs.
III E : largio of Intenolar eaiDcoce SfP
SuI I filifora papillae
U P
l i dd l e filifor a papillae
UP
Large f iIi for a papillae
Scale bar
500 /L a
548
Fig. 3. Upper view of the composite photograph corresponding to the square insets of A-C in Fig. 2. In Figs. A and B, SfP on the meso-dorsal surface, MfP on the MIME, and UP on the 1ME are shown as well as in Fig. C on the IME .
...
Fig. 2. Upper view of a composite photograph of one of the scanning electron photomicrographs with low magnification of MVCS of the meso-dorsal surface of the rabbit tongue corresponding to the square inset of B-zone in Fig. 1.
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cannulated and prepared for macroscopic, stereomicroscopic and SEM observation. For SEM observations, each tongue was rinsed with 0.9% physiological saline solution or Ringer's solution at 35-37°C. Vascular perfusion with 0.9% physiological saline solution or Ringer's solution was then carried out until the lingual veins were refilled by the solution, and 5% glutaraldehyde solution in phosphate buffer (pH 7.4) was injected into
Fig. 4. Upper view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of SfPs whose concave network-like face pointed in an anterior direction, consisting of the ascending and descending capillary branches and composed of geometrically regular microvascular structures.
both the lingual arteries for fixation of the vessels and their tributaries. Both lingual arteries were filled with synthetic resin (Mercox CL-2R 5, CL-2B 5, CL-2C 5, Dainippon lnki Chemical Co., Ltd. Tokyo, Japan) under manual pressure and the injected specimens were fixed for 0.3 hrs at room temperature and kept for 0.3 hrs at 55°C in an incubator. The specimens were then polymerized completely, and im-
Fig.5. Anterior view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of SfPs the concave network-like face of which consists of microvascular structures. They are arranged geometrically and regularly.
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mersed in 20% KOH or NaOH solution for over 3 hrs at room temperature until the surrounding soft tissues were dissolved. The finest macerated vascular samples were carefully washed 23 times with running distilled warm tap water at 45-50°C and gently dried for 2-3 days at 55°C in an incubator. The MVCS of the whole tongue were mounted on specimen stubs, and coated by platinum sputtering. The specimens were then examined with a S-4000 scanning electron microscope (HITACHI, Tokyo, Japan) at an accelerating voltage of 5 kV.
MfPs . The LfPs are wider and longer than the MfPs. LfPs form a long triangle-like concave structure with a sharper arrowhead-like top facing in an anterior direction and inclined in a posterior direction (pharynx). They cover the whole swelling dorsal area of the IME (Fig. 2, Fig. 3 A-C, Fig. 7 A-C).
Results Macroscopically, the rabbit tongue is relatively narrow and long (in the adult approximately 7.0 em long, 2.5 em wide and 1.0 em deep), running from the apex (anterior) in the direction of the root (posterior) with a rounded tip in front. It is composed of three regions, the anterior (Fig. 1, A-zone), middle or intermolar eminence (IME) (Fig. 1, B-zone) and the posterior region (Fig. 1, C-zone) on the dorsal surface of the lingual body. In the middle dorsal surface region, the !ME (Fig. 1) is located longitudinally and forms a long arrowhead-like swelling from the center towards the pharynx. Six kinds of lingual papillae were observed, the small filiform papillae (SfP) (Fig. 1, Fig. 2, and Fig. 3 A and B) and fungiform papillae (FuP) in the anterior region, except for the IME and their marginal parts, the middle filiform papillae (MfP) (Fig. 1, Fig. 2 and Fig. 3 A and B) on the marginal part of IME (MIME) (Fig. 2), the large filiform papillae (LfP) (Fig. 1, Fig. 2 and Fig. 3 A-C) on whole area of the IME (Fig. 2), the foliate papillae (FoP) on both the posteroperipheral sides and circumvallate papillae (CvP) located behind the FoP on both sides posteriorly. FoPs and CvPs are located symmetrically on both sides of the midline (Fig. 1). In the present study, the microvascular morphological characteristics and pattern of distribution were investigated by means of MVCS of SfPs, MfPs and LfPs, composed primarily of the ascending and descending capillary branches, on the meso-dorsal surface (B-zone) of the rabbit tongue with th e SEM in detail (Figs. 2, 3). SfPs covered all the meso-dorsal surface, except for the IME and MIME, and faced their concave aspect, consisting of a spoon-like network structure, in an anterior direction. Their arrowhead-like tips inclined in a posterior direction geometrically and regularly (Fig. 2, Fig. 3 A and B, Fig. 4 A-C, Fig. 5 A-C). The outer frame of MfPs consists of the ascending and descending branches and the y are slimmer and longer than the SfPs. Their long triangle-like concave network structures, the tops of which are sharper than th at of SfPS, faced in an anterior direction. MfPs surround both the peripheral and anterior parts of the margin of IME and are at right angles to the swelling IME (Fig. 2, Fig. 3 A and B, Fig. 6 A-C). The outer frame of the LfPS forms the ascending and descending capillary branches as well as those of SfPs and
Fig. 6. Anterior view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of MfPs the outer frame of which consisted of ascending and descending capillary branches which are slimmer and longer than SfP. Their long triangle-like concave network microvascular structures are in an arrowhead-like shape the top of which is sharper than that of SfPsfacing in an anterior direction.
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Discussion Although many ultrastructural morphological studies have been done on the lingual papillae of the rabbit tongue, relatively few have dealt with the microvascular structure and functional classification of FiP on the mesodorsal surface of the tongue. The purpose of this study was to undertake a detailed SEM three-dimensional observation of the morphological characteristics of MVCS of FiP on the meso-dorsal surface of the rabbit tongue. This is composed of the dorsal surface, the MIME and IME, and classified SfP on the dorsal surface, except for the MIME and IME, MfP on the MIME and LfP on the IME. As described by Hellekant (1971), the blood supply to the tongue is more plentiful than that of most other tissues, and it may be reasonable to suppose that the blood vessels inside the lingual papillae of the tongue form its basic structural core. The MVCS methods applied in this study (Ojima et al. 1997a-e) provided a relatively practical and useful observational method for studying the three-dimensional architecture of the microvascular network structure of FiP (SfP, MfP and LfP) of the rabbit tongue. The author could observe MVCS of FiP under better specimen conditions and obtained good photomicrographs with the SEM. There are no comparative descriptions entering into details of the classificatory relationships between the angioarchitectural structure and functional distributive pattern in the reference book on the rabbit (Borone et al. 1973). The tongue of the rat in the SEM (Stereoscan) (Svejda and Skach 1971), differentiation of lingual filiform papillae of the rat on organ culture (1973), morphogenesis of the rat lingual filiform papillae (Bratze and Farbman 1975), three-dimensional and surface structures of rat filiform papillae (Iida et al. 1985), morphological studies of rat lingual filiform papillae (Nagato et al. 1989), a developmental map of the connective tissue core and microvasculature of the filiform papillae (Okada et al. 1994), a microvascular structural study of the filiform papillae in the cat tongue (Ojima and Lowe 1995), and the distributive pattern, form and function seen in microvascular cast specimens of filiform papillae on the anterodorsal surface of the adult rat tongue (Ojima et al. 1996c) have all been carried out. Also comparative studies of the dorsal surface of the Fig. 7. Anterior view of scanning electron photomicrograph with low (A), middle (B) and high magnification (C) of MVCS of tongue in three mammalian species by SEM (Iwasaki et UPs which are wider and longer than those of MfPs. Their long al. 1987), comparative studies on the stereo-architecture triangle-like concave network microvascular structure faces in an of the connective tissue papillae in some mammalian tonanterior direction and the arrowhead-like shape, the top of gues (Kobayashi and Iwasaki 1988) and angioarchitecturwhich is sharper and longer than that of MfPs, is inclined in a al comparison of the filiform papillae of the cat and posterior direction (pharynx). rabbit using scanning electron microvascular specimens Scale bar in Figs. 3A-C-7 A-C =100 urn, The arrows at the (Ojima et al. 1996b) have also been done. upper and lower parts and at right and left in Figs. 1 and 2 and The present study was carried out to obtain further inFigs. 3 A-C-7 A-C indicate the anteriordirection. formation on the three kinds of FiP: SfP, MfP and LiP. On the basis of the results, from the morphological characteristics of MVCS of FiP observed by means of the
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SEM, PiP can be classified into three kinds: SiP on the Ojima K, Lowe AA (1995) Microvascular structural study of the filiform papillae in the cat tongue. Shigaku (Odontology) 82: meso-dorsal surface, except for the MIME and IME, MiP 1325-1336 on the MIME and LiP on the IME according to the size, shape and directional pattern. Each FiP aspect is com- Ojima K, Takeda M, Saiki C, Matsumoto S (1996 a) Functional and morphological observations on the microvascular strucposed of the ascending and descending capillary l?ops, i~ ture of the filiform and fungiform papillae in the cat tongue. clined in a posterior direction (pharynx) and with their Ann Anat 178: 361-364 concave face pointed in an anterior direction. Ojima K, Takeda M, Saiki C, Matsumoto S (1996 b) AngioarchiSfP, MiP and LiP playa mechanical role, that is, mastitectural comparison of the filiform papillae of the cat and rabcation and transporting water and the masticated food bit using scanning electron microscopic specimens. Ann Anat 178: 449--454 mass towards the pharynx in cooperation with each other Ojima K, Saiki C, Matsumoto S, Takeda M (1996 c) The distribuon the meso-dorsal surface of the rabbit tongue.
References Borone R, Pavaux C, Blin PC, Cuq P (1973) Atlas D' Anatomie du Lapin. Masson & Edutiturs, Paris, pp 75-78 Baratz RS, Farbman AI (1975) Morphogenesis of rat lingual filiform papillae. Am J Anat 143: 283-302 Chamoro CA, Sandoval J, Fernandez JG, Fernandez M, de Paz P (1987) Comparative study of the lingual papillae of cats (Felis catus) and rabbits (Oryctolagus cuniculus) using the scanning electronic microscope. Anat Histol Embryo 16: 37--47 Farbman AM (1973) Differentiation of lingual filiform papillae of the rat in organ culture. Arch Oral Biol 18: 197-202 Hellekant G (1971) Circulation of the tongue. In: Emmelin N, Zotterman Y (Eds) Oral Physiology. Pergamon Press, Oxford, pp 127-137 Iida M, Yoshioka I, Muto R (1985) Three-dimensional and surface structures of rat filiform papillae. Acta Anat 21: 237-244 Iwasaki S (1987) Morphological studies of the lingual mucosa of the rabbit. Fine structure of the mucosal epithelium. Shigaku (Odontology) 74: 1235-1264 Iwasaki S, Miyata T, Kobayashi K (1987) Comparative studies of the dorsal surface of the tongue in three mammalian species by scanning electron microscopy. Acta Anat 128: 140-146 Kobayashi K, Iwasaki S (1988) Comparative studies on the stereo architecture of the connective tissue papillae in some mammalian tongues. Prog Clin BioI Res 259: 303-308 Kobayashi K, Asami T, Kitajima K, Takahashi K, Iwasaki S (1989) Stereo structure of the connective tissue papillae of the rabbit tongue. Acta Anat Nippon 64: 224-232 Kobayashi K (1992) Comparative anatomical studies on the tongues with special reference to the connective tissue cores of the lingual papillae. Shigaku (Odontology) 80: 661-678 Nagoto T, Nagaki M, Murakami M, Tanioka R (1989) Morphological studies of rat lingual filiform papillae. Okajima Folia Anat Jpn 66: 195-210
tive pattern, form and function seen in microvascular cast specimens of filiform papillae on the anterodorsal surface of the adult rat tongue. Ann Anat 178: 531-535 Ojima K, Takeda M, Saiki C, Takahashi T, Matsumoto S (1997 a) A-form distribution seen in microvascular cast specimens of the filiform and fungiform papillae on the anterior central dorsal surface of the cat tongue. Ann Anat 179: 201-208 Ojima K, Takahashi T, Takeda M, Matsumoto S, Saiki C (1997 b) Angioarchitectural comparison of the fungiform papillae of the cat and rabbit using scanning electron microscopic specimens. Ann Anat 179: 209-214 Ojima K, Takeda M, Matsumoto S, Saiki C, Takahashi T (1997 c) Functional role of V form distribution seen in microvascular cast specimens of the filiform and fungiform papillae on the posterior central dorsal surface of the cat tongue. Ann Anat 179: 321-327
Ojima K, Matsumoto S, Saiki C, Takahashi T, Takeda M, Mitsuhashi F (1997 d) Angioarchitectural structure of the fungiform papillae on the anterodorsal surface of the rabbit tongue. Ann Anat 179: 329-333 Ojima K, Takeda M, Matsumoto S, Nakanishi I (1997 e) Microvascular fin-like structure of the foliate papillae of the rabbit tongue using scanning electron microscopic specimens. Ann Anat 179: 511-515 Okada S, Ohta M, Yoshida S (1994) Developmental map of the connective tissue core and microvasculature of the filiform papillae. Dentistry 31: 9-16 Shimamura A, Tokunaga J, Toh R (1972) Scanning electron microscopic observation on the taste pores and taste hairs in rabbit gustatory papillae. Arch Histol Jap 34: 51-60 Svejda J, Skach M (1971) Die Zunge der Ratte im Raster-Elektronenmikroskop (Stereoscan). Z mikrosk anat Forsch 84: 101-116
Toyoshima K, Shimamura A (1982) Scanning electron microscope study of the epithelium-connective tissue interfaces of the tongue pepillae in the rat. Jpn J Oral Biol 24: 1019-1022 Accepted June 10, 1998
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