Three-dimensional structure of the connective tissue core of the lingual papillae in the crab-eating macaque (Macaca fascicularis)

The three-dimensional structure of the connective tissue core (CTC) of the four types of lingual papillae of the crab-eating macaque (Macaca fascicularis) was studied by scanning electron microscopy after removal of the epithelial cell layer by long-term treatment with hydrochloric acid at room temperature and compared with the results obtained from light microscopy. 1) Filiform papillae are densely distributed on the dorsal surface of the anterior two thirds of the tongue. Fungiform papillae are scattered among these filiform papillae, and are numerous at the anterior margin of the tongue. The connective tissue core of each filiform papilla looked like a lifting human hand with its palm towards the tongue tip. By using light microscopy, AF-positive elastic fibers were accumurated very densely just beneath the basal region of the anterior column epithelium of each filiform papilla. 2) CTC of fungiform papilla showed coralliform structure whose branches were ramified a few times. On the top of each branch there was a small depression where a taste bud was situated. 3) After removal of the epithelial cell layer of the foliate papilla, longitudinal grooves coinciding with the epithelial slits were observed. Some glandular ducts were seen protruding towards the exfoliated epithelium. 4) After removal of the covering epithelium of the vallate papilla, numerous small rod-shaped secondary CT cores appeared on the large primary CT core.     

Immunohistochemical expression of keratins 13 and 14 in the lingual epithelium of rats during the morphogenesis of filiform papillae

We examined the immunofluorescence of keratins 13 (K13) and 14 (K14) and differential interference contrast (DIC) images during the morphogenesis of filiform papillae and the keratinization of the lingual epithelium of rats on semi-ultrathin sections of epoxy resin-embedded samples by laser-scanning microscopy. We also examined semi-ultrathin sections of epoxy resin embedded, toluidine blue stained samples by light microscopy to obtain details of cell histology and morphology. No immunoreactivity specific for K13 and K14 was detected on the lingual epithelium of foetuses on days 13, 15 and 17 after conception (E13, E15 and E17), during which time the number of layers of cuboidal cells in the lingual epithelium increased from one to several. Immunoreactivity specific for K13 and K14 was first detected on the lingual epithelium of foetuses on E19. The immunoreactivity specific for K13 appeared in the suprabasal cells of the papillary and interpapillary cell columns and immunoreactivity specific for K14 was detected in the basal and suprabasal cells of the papillary and interpapillary cell columns. The lingual epithelium was composed of stratified squamous cells. The rudiments of filiform papillae were compactly arranged and interpapillary cell columns were very narrow. Filiform papillae developed gradually from postnatal day 0 (PO) to 21 (P21). The width of interpapillary spaces also increased during this period. Immunoreactivity specific for K13 and K14 was distinct at all postnatal stages examined. Thus, the patterns of immunoreactivity of K13 and K14 differed as the filiform papillae developed.     

Immunohistochemical detection of the expression of keratin 14 in the lingual epithelium of rats during the morphogenesis of filiform papillae

An immunofluorescence study of the expression of keratin 14 (K14) during the formation of filiform papillae was performed and the progress of keratinization of the epithelium of the rat tongue was monitored on semi-ultrathin sections by laser-scanning microscopy. Differential interference contrast (DIC) images were also examined to provide details of histology and cell morphology. No cells with immunoreactivity specific for K14 were detected on the lingual epithelium of foetuses on embryonic days 12 and 16 (E12 and E16), when the lingual epithelium was composed of a single layer or several layers of cuboidal cells. Immunoreactivity specific for K14 was detected first on basal and suprabasal keratinocytes of the dorsal epithelium of the tongue of new-borns on postnatal day 0 (P0) and was conspicuous in juveniles on P14. The immunoreactivity was particularly strong on the basal and suprabasal keratinocytes along the connective tissue papillae. The immunoreactivity extended over the entire cytoplasm but was not detected in the nucleus. The lingual epithelium was composed of stratified squamous cells and the rounded rudiments of filiform papillae were compactly arranged at equal intervals, for the most part, and the spaces between them were narrow and indistinct. Immunostaining of K14 was distinct on basal and suprabasal keratinocytes of the filiform papillar area of tongues of juveniles on P21, when the filiform papillae were conical. The spaces between them were relatively wide and, as a result, interpapillar cell columns were clearly visible. Immunoreactivity specific for K14 in the basal and suprabasal keratinocytes of the interpapillar cell columns was recognizable but was weaker than that in cells of papillar cell columns. The thickness of the epithelium in papillar and interpapillar areas increased gradually with the development of filiform papillae. However, sizes of basal and suprabasal keratinocytes remained almost unchanged during this process. These results suggest that the basal and suprabasal keratinocytes of the filiform papillar area proliferate with the initiation of the morphogenesis of filiform papillae and the keratinization of the epithelium. In addition, it appears that, after P14, the basal and suprabasal keratinocytes of the interpapillar area proliferate to supply the keratinocytes of the expanding interpapillar regions.     

Immunohistochemical expression of type II collagen in the lingual mucosa of rats during organogenesis of the tongue

OBJECTIVES: We examined the timing of the appearance and distribution of type II collagen as a possible component of the extracellular matrix that is involved in the morphogenesis of the rat tongue. METHODS: We examined the immunofluorescence of type II collagen, differential interference contrast (DIC) images, and images recorded in transmission mode after toluidine blue staining by laser-scanning microscopy (LSM) during the morphogenesis of filiform papillae and the keratinization of the lingual epithelium of rats on semi-ultrathin sections of epoxy resin-embedded samples. RESULTS: Immunoreactivity specific for type II collagen was scattered on cells over a wide area of the mesenchymal connective tissue of the fetal tongue on day 15 after conception (E15), when the lingual epithelium was composed of one or two layers of cuboidal cells. Immunoreactivity specific for type II collagen was recognisable on cells of the lamina propria of the lingual mucosa and around the developing lingual muscle of fetuses at E17 and E19. On E19, the epithelium was clearly of the stratified squamous type. At postnatal stages after birth (P0), immunoreactivity became more and more significant in the connective tissue of the lamina propria with the advancing of morphogenesis of the filiform papillae. In addition, immunoreactivity was widely distributed in the connective tissue around the lingual muscle, as myogenesis in the tongue advanced. The lingual epithelium was composed of stratified squamous cells, and keratinization of the lingual epithelium proceeded gradually as morphogenesis of filiform papillae continued during postnatal development. CONCLUSION: Type II collagen appeared not only in the connective tissue of the lamina propria as the morphogenesis of filiform papillae occurred and the lingual epithelium became keratinized but also in the endomysium and perimysium around the lingual muscle after myogenesis of the tongue is complete at P0.     

Immunohistochemical analysis of type III collagen expression in the lingual mucosa of rats during organogenesis of the tongue

We examined the distribution of immunofluorescence due to immunostaining of type III collagen, differential interference contrast (DIC) images and images obtained in the transmission mode after toluidine blue staining by laser-scanning microscopy of semi-ultrathin sections of epoxy resin-embedded samples, during morphogenesis of the filiform papillae, keratinization of the lingual epithelium, and myogenesis of the rat tongue. Immunoreactivity specific for type III collagen was distributed widely in the mesenchymal connective tissue in fetuses on day 15 after conception (E15), at which time the lingual epithelium was composed of one or two layers of cuboidal cells and the lingual muscle was barely recognizable. Immunoreactivity specific for type III collagen was clearly detected on the lamina propria in fetuses on E17 and E19, and it was relatively distinct just beneath the lingual epithelium. Immunoreactivity specific for type III collagen was sparsely distributed on the connective tissue around the developing lingual muscle. In fetuses on E19, the epithelium became clearly stratified and squamous. At postnatal stages from newborn (P0) to postnatal day 14 (P14), keratinization of the lingual epithelium advanced gradually with the development of filiform papillae. On P0, myogenesis of the tongue was almost completed. The intensity of the fluorescence immunoreactivity specific for type III collagen at postnatal stages was almost same as that on E19. The immunoreactivity around the fully mature muscle was relatively distinct between P0 and P14. Thus, type III collagen appeared in conjunction with the morphogenesis of filiform papillae and the keratinization of the lingual epithelium as well as in the connective tissue that surrounded the lingual muscle during myogenesis of the rat tongue.     

Morphological study of lingual papillae in the fetal cat at mid-gestation,as revealed by light and scanning electron microscopy

 Tongues were removed from five cat fetuses, after approximately 1 month of gestation, for examination by light and scanning electron microscopy. Rudiments of filiform papillae were visible over the entire dorsal surface of the tongue. The epithelium of the dorsal surface of the tongue was of the stratified cuboidal type. No evidence of keratinization was detected anywhere in the entire dorsal lingual epithelium. Rudiments of fungiform papillae were recognizable only at the lingual apex; none were recognizable on other parts of the dorsal surface of the tongue at this stage. By contrast, rudiments of circumvallate and foliate papillae were already distinguishable from the filiform papillae. Differences between these results and those obtained previously in rats and mice are discussed. Received: August 29, 2001 / Accepted: May 7, 2002     

A comparative morphological study on the tongue and the lingual papillae of some marine mammals —Particularly of four species of odontoceti and zalophus—

We observed the structure of the tongues of some aquatic mammals in four species of Odontoceti (Stenella coeruleoalba, Lagenorhynchus obliquidens, Tursiops truncatus andMesoplodon stejnegeri) andZalophus californianus californianus using light microscopy (LM) as well as scanning electron microscopy (SEM) and compared the characteristics of the tongue of each animal species. In the four species of Odontoceti, the dorsal surface of the anterior part of the tongues had a smooth surface. However, after removal of the epithelium, slender conical connective tissue cores (CTCs) were densely distributed. At the boundary between the lingual body and the root ofTursiops truncatus, several round vallate-like structures were observed and inLagenorhynchus obliquidens, they had a pair of V-shaped long fissures. In the shallow part of these fissures of both species, some taste buds were observed. Generally, the characteristics of the tongue of three species of dolphins were respectively more simple fromTursiops truncatus toLagenorhynchus obliquidens, toStenella coeruleoalba. InMesoplodon stejnegeri, the structure of the tongue showed further simplified characteristics. In the tongue ofZalophus californianus californianus, well-developed lingual papillae (e.g. filiform-, fungiform-, vallate papillae) were observed. Instead of foliate papillae, a series of finger-like long papillae were distributed. The tongue of theZalophus had typical lingual papillae similar to those of Carnivorae of land mammals.     

A scanning electron microscopic study of fissured tongue

In this study, scanning electron microscopy was used to describe the surface morphology of fissured tongue. Tissue samples from the anterior part of the tongue were taken from 15 patients with fissured tongue. The formalin-fixed samples were processed routinely for scanning electron microscopy. Typically, the surface of a fissured tongue was covered with hairless papillae of various sizes. The biggest papillae were larger than the body of a normal filiform papilla, and the apex was rounded and rough. On the other hand, some of these papillae had a few hairs and resembled normal filiform papillae, but were flatter. In addition some papillae formed only slight elevations on the tongue mucosa, which was smooth and contained some desquamating cells. The walls of the fissure found in macroscopical examination consisted of very low elevations of the smooth mucosa with some desquamating cells. At high magnification the superficial cells of the epithelium were polygonal. On their surface there were branching or parallel microplicae, which were often broken. Only occasionally superficial cells of the large papillae had a pitted appearance. The knob-like structures found among the microplicae and small cracks between the epithelial cells are discussed from the standpoint of the pathogenesis of fissured tongue.     

A scanning electron microscopic study of fissured tongue

In this study, scanning electron microscopy was used to describe the surface morphology of fissured tongue. Tissue samples from the anterior part of the tongue were taken from 15 patients with fissured tongue. The formalin-fixed samples were processed routinely for scanning electron microscopy. Typically, the surface of a fissured tongue was covered with hairless papillae of various sizes. The biggest papillae were larger than the body of a normal filliform papilla, and the apex was rounded and rough. On the other hand, some of these papillae had a few hairs and resembled normal filiform papillae, but were flatter. In addition some papillae formed only slight elevations on the tongue mucosa, which was smooth and contained some desquamating cells. The walls of the fissure found in macroscopical examination consisted of very low elevations of the smooth mucosa with some desquamating cells. At high magnification the superficial cells of the epithelium were polygonal. On their surface there were branching or parallel microplicae, which were often broken. Only occasionally superficial cells of the large papillae had a pitted appearance. The knob-like structures found among the microplicae and small cracks between the epithelial cells are discussed from the standpoint of the pathogenesis of fissured tongue.     

Scanning electron microscopy of the rat tongue mucosa with special attention to the bacteria on epithelial cell membranes

The authors examined the filiform and fungiform papillae surfaces of rat tongue by scanning electron microscopy showing the numerous groupings of bacteria on the epithelial cell membranes. The fungiform papillae were round in shape and present few bacteria. The epithelial cell of filiform papillae revealed numerous streptococci. The grouping of the bacteria are attached on the epithelial cell membrane, demonstrating three-dimensional SEM images.     

Lingua fissurata. A clinical, stereomicroscopic and histopathological study

The purpose of this study was to describe clinical, stereomicroscopic and light microscopic findings for fissured tongue in 17 patients and compare them with 17 normal controls. Clinical symptoms were found in 13 of 17 patients who complained of scoreness of the tongue. Usually the symptoms lasted more than 3 years. In 15 cases, fissures involved the entire tongue, while in 2 cases, only the edges of the tongue were affected. In all patients, papillae of varying sizes were found in the area of fissures. The papillae were easily noted using stereomicroscopy on fixed-tissue specimens, but could also be seen with the naked eye during careful clinical examinations. Light microscopic studies indicated that the number of inflammatory cells was far greater in the mucosa of fissured tongues than in normal tongues, and this inflammation was not confined only to the fissures. The rete pegs of the epithelium were longer in fissured tongues than in normal tongues, 800 (+/- 79) micron and 620 (+/- 69) micron, respectively, (p less than 0.001). The lamina propria was also thicker in fissured tongues than in normal tongues, 390 (+/- 74) micron and 170 (+/- 61) micron, respectively, (p less than 0.001). In normal tongues, keratohyaline granules were observed in the filiform papillae around the area of hairs but these granules were absent in fissured tongues.     

An Attempt at Replication of Human Lingual Papillae Using a Replica Method with Epoxy Resin

Using low viscous silicone impression material, we made a mold of the dorsal surface of living human tongues and successfully made precise replicas of lingual papillae with epoxy resin. Following a paradium coating, the epoxy resin replica was examined under a scanning electron microscope (SEM) and the images were compared with close-up photographs of the dorsal surface of the same tongue. Distribution patterns of fungiform papillae of the apical surface of the tongue varied in each individual. In epoxy resin replicas, bundles of fine slender protrusions of filiform papillae as well as taste pores of fungiform papillae of both living and fixed human tongues became apparent and easily distinguishable under an SEM.     

Stereo architecture of the connective tissue papillae of lips and gingiva in newborn dogs

The surface structure of the connective tissue papillae of lips and gingiva of newborn dogs 1 and 4 weeks after birth were observed by scanning electron microscopy. 1. Long term HCl treatment successfully removed the epithelial cell layer from the connective tissue over a large area of fixed material. 2. Connective tissue papillae of labial skin, labial mucosa and alveolar and gingival mucosa were exposed and it became clear that connective tissue papillae were highly developed at the labial margin and just beneath the gingival margin. 3. In the hair growing area of the labial skin, connective tissue papillae became smaller, and some ridge-like structures were found running vertically. 4. On the lining mucosa such as the labial and alveolar mucosa, the surface of the connective tissue papillae showed only ridge-like structures running vertically. 5. From the results of both light and electron microscopy, we concluded that there was a tendency for the area to have a thick epithelial cell layer which contained highly developed connective tissue papillae. This suggested that the blood vessels in the connective tissue papillae can carry nutrients closer to more epithelial cells penetrating deeply into the epithelium thickness.     

Bmp signalling in filiform tongue papillae development

ObjectiveTongue papillae are critical organs in mastication. There are four different types of tongue papillae; fungiform, circumvallate, foliate, and filiform papillae. Unlike the other three taste papillae, non-gustatory papillae, filiform papillae cover the entire dorsal surface of the tongue and are important structures for the mechanical stress of sucking. Filiform papillae are further classified into two subtypes with different morphologies, depending on their location on the dorsum of the tongue. The filiform papillae at the intermolar eminence have pointed tips, whereas filiform papillae with rounded tips are found in other regions (anterior tongue). It remains unknown how the shape of each type of filiform papillae are determined during their development. Bmp signalling pathway has been known to regulate mechanisms that determine the shapes of many ectodermal organs. The aim of this study was to investigate the role of Bmp signalling in filiform papillae development.DesignComparative in situ hybridization analysis of six Bmps (Bmp2–Bmp7) and two Bmpr genes (Bmpr1a and Bmpr1b) were carried out in filiform papillae development. We further examined tongue papillae in mice over-expressing Noggin under the keratin14 promoter (K14-Noggin).ResultsWe identified a dynamic temporo-spatial expression of Bmps in filiform papillae development. The K14-Noggin mice showed pointed filiform papillae in regions of the tongue normally occupied by the rounded type.ConclusionsBmp signalling thus regulates the shape of filiform papillae.     

舌神经修复效果及评价方法的初步研究

本研究目的是评价舌神经吻合后舌前２／３感觉和味觉恢复的情况。应用神经外膜吻合修复舌神经损伤１４例，初步研究结果表明：①舌神经重度损伤后，患侧舌前２／３菌状乳头大多萎缩、消失，感觉和味觉严重障碍；②神经外膜吻合修复舌神经，菌状乳头可以再生，术后一年，５０％患者感觉恢复正常，３５．７１％患者味觉恢复正常；③感觉功能检查、味觉功能测定、菌状乳头及其味孔定量观察评价舌神经的损伤和修复，结果是客观、准确、可靠的。     

Localization of type III collagen in the lingual mucosa of rats during the morphogenesis of circumvallate papillae

In an effort to identify a possible role for type III collagen in the morphogenesis of circumvallate papillae on the surface of the rat tongue, we examined its appearance by fluorescent immunostaining, in conjunction with differential interference contrast images and images obtained, after staining with toluidine blue, in the transmission mode by laser-scanning microscopy. We analyzed semi-ultrathin sections of epoxy resin-embedded samples of the lingual mucosa of embryonic and juvenile rats, 13 days after conception (E13) to day 21 after birth (P21). Immunoreactivity specific for type III collagen was recognized first in the mesenchymal connective tissue just beneath the circumvallate papilla placode in fetuses on E13. At this stage, most of the lingual epithelium with the exception of the circumvallate papilla placode was pseudostratified epithelium composed of one or two layers of cuboidal cells. However, the epithelium of the circumvallate papilla placode was composed of several layers of cuboidal cells. Immunoreactivity specific for type III collagen was detected mainly on the lamina propria just beneath the lingual epithelium of the rudiment of the circumvallate papilla and the developing circumvallate papilla in fetuses on E15 and E17, and slight immunostaining was detected on the lamina propria around the rudiment. In fetuses on E19, immunoreactivity specific for type III collagen was widely and densely distributed on the connective tissue around the developing circumvallate papillae and, also, on the connective tissue that surrounded the lingual muscle. However, the immunoreactivity specific for type III collagen was sparsely distributed on the lamina propria of each central papillar structure. After birth, from P0 to P14, morphogenesis of the circumvallate papillae advanced gradually with the increase in the total volume of the tongue. At these postnatal stages, the intensity of the fluorescence due to immunoreactivity specific for type III collagen was distinctively distributed on the lamina propria around each circumvallate papilla, on each central bulge and on the connective tissue that surrounded the lingual muscle. However, immunofluorescence was less distinct on the connective tissue that surrounded the lingual muscle. Thus, type III collagen appeared in conjunction with the morphogenesis of the circumvallate papillae, as well as in the connective tissue that surrounded the lingual muscle during myogenesis of the rat tongue.     

Details of the intralingual topography and morphology of the lingual nerve

The lingual nerve supplies the tongue with trigeminal sensory fibers and sensory fibers that originate from the chorda tympani. The aim of this study was to investigate, by dissection, the anatomical features of the lingual nerve at the level of the tongue and to correlate the findings with existing data. Six human adult cadavers dissected bilaterally and 6 specimens of tongue-pharynx-larynx from autopsied adult cadavers were studied. The lingual nerve gives off its terminal branches at the anterior border of the hyoglossus muscle where the anastomotic loops between the lingual and hypoglossal nerves are found. Two morphological types of terminal division of the lingual nerve were seen: a single primary trunk or two primary trunks, a medial one distributed in the middle third of the tongue and a lateral one for the anterior third of the tongue. The primary terminal branches of the lingual nerve were located on the outer surface of the genioglossus muscle, forming a nervous layer over the deep artery of the tongue. The following emerged from the primary trunk(s): thin branches for the ipsilateral mucosa of the ventral surface of the tongue and 4-9 thick secondary trunks, with palisade disposition and translingual courses that followed the outer surface of the genioglossus muscle towards the dorsal mucosa of the ipsilateral part of the tongue, anterior to the circumvallate papillae.     

Microvasculature of the dorsum of the rat tongue: a scanning electron microscopic study using corrosion casts

The purpose of this study was to examine the microvascular system of the dorsum of the rat tongue in relation to the subepithelial connective tissue relief. Methylmethacrylate corrosion casts of the vasculature as well as specimens in which the epithelium had been removed were prepared and examined by scanning electron microscopy (SEM). The SEM images revealed four distinct layers in the vasculature of the lamina propria. Superficially, Layer 1 comprised the irregularly shaped ends of capillary loops. Layer 2 consisted of parallel ascending and descending capillaries. These two layers were drained by the subjacent Layer 3, a fish-net-like venous plexus. More deeply, Layer 4 contained arterioles ascending from the muscular layers of the tongue. The vessels of larger papillary structures formed cylindric networks supplied by several arterioles and drained through a single venule to the venous plexus in Layer 3. At their base, the capillary loops often showed a constriction, suggestive of a sphincter. Arteriovenous anastomoses were rare. The epithelium-connective tissue interface showed short conical papillae as well as larger papillary structures which corresponded in both distribution and size to the capillary loops found in the vascular casts. The results confirm that the tongue is highly vascularized and demonstrate that the vascular supply to the papillae, taste buds, and other surface structures forms a highly organized and specific system which is adapted to the specific functions of this organ in the rat.     

A histological study of changes in the lingual papillae of streptozotocin-induced diabetic rats.

This study examined the effect of experimental diabetes mellitus on the dorsal tongue of rats which were made diabetic by tail-vein injections of streptozotocin (50 mg/kg) and then raised for either 5 or 10 months. Lingual papillae were observed by scanning electron microscopy (SEM) and light microscopy. Morphological changes in lingual mucosal capillaries in 10-month diabetic rats were observed by electron microscopy (TEM). In the study of cellular movement in the lingual dorsal epithelium, bromodeoxyuridine (BrdU) was applied as a tracer for studying DNA replication. In diabetic rats, lingual papillae showed morphological atrophic changes. The lingual mucosal capillaries' alterations included endothelial cells with numerous cell projections into the lumen, degenerated cell organs, increased basement membrane width, and narrowed capillary lumen. BrdU labeling index among the basal cells was reduced in diabetic rats which indicates a possible retardation of their epithelial-tissue activity. In diabetes mellitus, direct metabolic disturbances to the epithelia because of insulin deficiency first occurred, successively diabetic microangiopathy appeared on the lingual mucosal capillaries. The appearance of diabetic microangiopathy caused tissue hypoxia, which induced atrophic changes to the epithelia.     

Scanning electron microscopy of the epithelium-connective tissue interfacein human gingiva

The morphological characteristics of the interface between epithelium and connective tissue in normal human gingiva were examined by scanning electron microscogy after separation of epithelium and connective tissue by maceration in sodium bromide solution. Separated crevicular epithelium showed dispersed arcade-shaped pits corresponding to long conical connective tissue papillae. In the epithelium and connective tissue of the free gingiva, horizontal ridges ran parallel to the gingival margin. At the transition from free gingiva to attached gingiva, short conical connective tissue papillae arose from horizontal connective tissue ridges. Toward the alveolar mucosa these papillae increased in number, forming a honeycomb pattern on the separated epithelial surface.