Morphology of the lingual papillae in the raccoon dog and fox

The dorsal lingual surfaces of the raccoon dogs (Nyctereutes procyonoides) and fox (Vulpes vulpes japonica) were examined by scanning electron microscopical (SEM) observations. The distribution and type of the lingual papillae found in the raccoon dog were similar to those in the fox. Filiform, fungiform, foliate and vallate papillae were observed. The filiform papillae were distributed over the entire dosal surface of the tongue. Each filiform papilla on the apical surface of the tongue had several pointed processes. The filiform papillae of the lingual body consisted of a main papilla and some secondary papillae. The fungiform papillae were present rounded bodies, and more densely distributed on the lingual apex. The foliate papillae were seen on the dorsolateral aspect of the tongue. The vallate papillae were located on both sides of the posterior end of the lingual body. Each papilla was surrounded by groove and crescent pad. On the periphery of the papillae, large conical papillae were observed.     

Morphology of the dorsal lingual papillae in the blackbuck, Antilope cervicapra

The dorsal lingual surface of a blackbuck (Antilope cervicapra) was examined by scanning electron microscopy (SEM). The tongue was about 125 mm in length. There were about 30 vallate papillae on both sides. Filiform, conical, fungiform and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue, excepted for the lingual torus where conical papillae were present. The fugiform papillae were present rounded bodies, and more densely distributed on the tip and ventral surface of ligual apex. No foliate papillae were seen on the dorsal surface. The vallate papillae were located on both sides of the midline in the caudal part. Each papilla was surrounded by a groove. These findings indicate that the tongue of the blackbuck is similar to that of the formosan and japanese serow.     

Morphology of the dorsal lingual papillae in the barbary sheep, Ammotragus lervia

The dorsal lingual surface of a barbary sheep (Ammotragus lervia) was examined by scanning electron microscopy (SEM). The tongue was about 20 cm in length. There were about 30 vallate papillae on both sides. Filiform, conical, fungiform and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue, excepted for the lingual torus where conical papillae were present. The fungiform papillae were present rounded bodies, and more densely distributed as compared to that of the lingual body on the tip and ventral surface of lingual apex. No foliate papillae were seen on the dorsal surface. The vallate papillae were located on both sides of the midline in the caudal part. Each papilla was surrounded by a groove. These findings indicate that the tongue of the barbary sheep is similar to that of the formosan serow, japanese serow and blackbuck.     

Morphology of the dorsal lingual papillae in the newborn panther and Asian black bear

The dorsal lingual surfaces of a newborn panther (Panthera pardus) and two newborn asian black bears (Selenarctos thibetanus) were examined by scanning electron microscopy (SEM). The tongues of the panther and asian black bear were about 40 mm in length and about 20 mm in width. Filiform, fungiform and vallate papillae were found. The filiform papillae were distributed over the entire dorsal surface of the tongue. In the panther, the filiform papillae on margin of the lingual apex were divided into two shapes which were horny or club-shaped papillae. The filiform papillae on the midportion were larger than those on the lateral region in size. The fungiform papillae also were divided into two shapes which were hemispherical or club-shaped papillae. In the asian black bear, the filiform papillae on the margin of the lingual apex were larger than those on margin of the panther tongue. The vallate papillae in the animals of two species were located on both sides of the posterior end of the lingual body. Each papilla was surrounded by a groove and crescent pad.     

Morphology of the lingual papillae in the sitatunga

We examined the dorsal lingual surfaces of an adult sitatunga (Tragelaphus spekei) by scanning electron microscopy. Filiform, fungiform and vallate papillae were observed. The filiform papillae consisted of a larger main papilla and smaller secondary papillae. The filiform papilla contained connective tissue core consisting of several processes. The fungiform papillae were round in shape. The connective tissue core of the fungiform papilla was flower-bud shaped. Lenticular papillae were limited on the torus lingua. The connective tissue core of the lenticular papilla consisted of numerous small spines, or these spines and rod-shaped processes. The vallate papillae were flattened-oval shaped and the papillae were surrounded by a circular trench. The connective tissue core of the vallate papilla was covered with numerous small spines. These findings indicate that the tongue of the sitatunga is similar to that of the blackbuck and Barbary sheep.     

Morphology of the lingual papillae in the tiger

The dorsal lingual surfaces of an adult tiger (Panthera tigris altaica) was examined by macroscopical and scanning electron microscopical observations. Filiform, fungiform and vallate papillae were observed. The filiform papillae were distributed over the entire dosal surface of the tongue. The fungiform papillae were present rounded bodies, and more densely distributed on the lingual apex. There were 4 vallate papillae in total on borderline between the lingual body and lingual radix. Each papilla was surrounded by a groove. No foliate papillae were seen on the dorsal surface. Openings of the glandular ducts on the regions of the vallate papillae were found.     

Morphology of the lingual papillae in the Patagonian cavy

We examined the dorsal lingual surfaces of an adult Patagonian cavy (Dolichotis patagonum) by scanning electron microscopy. The tongue of the Patagonian cavy is about 8 cm long and the lingual body had lingual prominence on the posterior third. There were no fungiform papillae in the lingual dorsal surface. The fungiform papillae were observed in both lateral sides of the lingual apex. The filiform papilla of the lingual body consisted of a large conical papilla. The connective tissue core of the filiform papilla showed many slender processes. The fungiform papillae were round in shape. The connective tissue core of the fungiform papilla was flower-bud shaped. Two vallate papillae were located on between lingual body and root, and insert in two grooves. The connective tissue core of the vallate papilla was covered with numerous small spines. Many foliate papillae were observed on the posterolateral regions of the tongue. After removing epithelium from the foliate papillae many vertical depressions became apparent. These findings suggest that in the structure of the lingual papillae of the Patagonian cavy there is similar to that of the capybara.     

Morphology of the lingual papillae in the Japanese marten

The dorsal lingual surfaces of two adult Japanese marten (Martes melampus) were examined by scanning electron microscopy (SEM). Filiform, fungiform, vallate and foliate papillae were observed. A small filiform papilla on the apical surface of the tongue had several pointed processes. A small filiform papilla contained the connective tissue core consisting of several small processes. A large filiform papilla of the lingual body consisted of a main papilla and some secondary papillae. A large filiform papilla contained the connective tissue core consisting of processes of various size. The fungiform papillae are round in shape. The connective tissue core of the fungiform papilla had a top with several round depressions. The four vallate papillae were located on both sides of the posterior end of the lingual body and each papilla was surrounded by groove and crescent pad. A zigzag surface structure appeared on the connective tissue core of the vallate papilla. The foliate papillae were seen on the dorsolateral aspect of the tongue and some ridges and grooves were exposed reciprocally. A zigzag surface structures appeared on the connective tissue cores of the ridges of the foliate papillae.     

Morphology of the lingual papillae in the roan antelope

We examined the dorsal lingual surfaces of an adult roan antelope (Hippotragus equinus) by scanning electron microscopy. Filiform, fungiform and vallate papillae were observed. The filiform papillae consisted of a larger main papilla and smaller secondary papillae. A top of the connective tissue core of the filiform papilla showed several depressions. The connective tissue core of the papilla with a long process was rarely observed. The fungiform papillae were round in shape. The connective tissue core of the fungiform papilla was flower-bud shaped. The lenticular papillae of large size were limited on the torus lingua. The connective tissue core of the lenticular papilla consisted of numerous small spines. The vallate papillae were located on both sides of the posterolateral aspects. The vallate papillae were flattened oval shaped and the papillae are surrounded by circular trench. The connective tissue core of the vallate papilla was covered with numerous small spines.     

SEM examination of the dorsal lingual papillae of pregnant rats

To our knowledge there are no histomorphological studies examining the lingual papillae in pregnancy. Therefore, this present study was planned. The purpose of this study was to clarify different physiological results and to investigate whether there are any changes on the dorsal surface of the rat tongue during pregnancy. On days 7 and 14 of pregnancy, superficial epithelial configurations of the lingual papillae (circumvallate, fungiform, filiform) in pregnant rats were examined by scanning electron microscopy (SEM). It was found that there were some differences in topographic configurations of these papillae in pregnant rats compared with controls. The obtained changes by SEM may reflect something which occurs in the lingual papillae during pregnancy in rat. There may be a correlation between the alterations of some hormone levels in pregnancy and some morphological changes of the lingual papillae.     

Morphology of the lingual papillae and their connective tissue cores in the cape hyrax

The dorsal lingual surfaces of four adult cape hyraxes (Procavia capensis) were examined by scanning electron microscopy (SEM). Filiform, fungiform and foliate papillae were observed. The lingual body had lingual torus on the posterior third. In the lateral sides of the tongue large fungiform papillae were observed and in the lateral sides of the torus very developmental foliate papillae were observed. Many fungiform papillae were observed in the ventral surface of the lingual apex. No vallate papillae were seen on the dorsal surface. The filiform papilla on the apical surface of the tongue had shovel-shaped papilla. The filiform papilla contained the connective tissue core consisting of some processes. The connective tissue core of the fungiform papillae was floral bud in shape. In the surface of the lingual torus numerous dome-shaped papillae are found. The dome-shaped papilla contained the connective tissue core consisting of a zigzag surface structure and the connective tissue core is surrounded by the processes of various sizes. In the surface of the lingual root numerous openings of the lingual glands were found. Around the glandular openings connective tissue ridges formed circular sheaths. In the lateral sides of the tongue large fungiform papillae were round in shape. The connective tissue core of the fungiform papilla was floral bud in shape. The foliate papillae were seen on the dorsolateral aspect of the tongue and some ridges and grooves were exposed reciprocally. Many small protrusions appeared on the connective tissue core of the ridge of the foliate papilla. These findings suggested that in the structure of the lingual papillae of the cape hyrax there was intermediate type between Rodentia and Artiodactyla.     

Morphogenesis of rat lingual filiform papillae

The morphogenesis of filiform papillae on rat tongue was investigated with the electron microscope. Tongue rudiments were first seen on the 12th day of gestation. At 15–17 days, dermal papillae had formed and were arranged in hexagonal array on the dorsal lingual surface. Capping each dermal papilla was a two-layered epithelium that protruded slightly above the lingual surface, thus forming the early filiform papilla. In the next stage of development, at 18–19 days of gestation, the epithelium lining the papilla had differentiated into two cell populations, one producing hard keratin, the other producing soft keratin. Some of the keratinized epithelial cells assumed a position at an acute angle to the tongue surface and extended deep into the epithelium. In the next stage, 20–21 days, a cleft appeared within these angularly oriented cells. This resulted in the division of the epithelium into keratin-lined individual filiform papillae. Finally, the individual papillae increased in size to the adult form.     

Role of IGFBPs in the morphogenesis of lingual papillae

The expression of insulin-like growth factor binding proteins (IGFBPs) during the morphogenesis of lingual papillae of mice was examined by in situ hybridization. Among seven mouse IGFBPs, IGFBP-1, -6, and -7 mRNAs were not expressed in the tongue tissue. At E12, though no papillae have formed yet, IGFBP-2, -4, and -5 were expressed in the entire tongue epithelium. At E14, fungiform papillae appeared in the anterior region and circumvallate papillae were distinguished in the posterior region. Strong expression of IGFBP-5 was observed in the apical region of both fungiform and circumvallate papillae. At this stage, the epithelial elevation of filiform papillae was not clear; but IGFBP-5 was expressed in the apex. At E15, foliate papillae were distinguished and IGFBP-5 was expressed in the dorsal epithelium of ridges. In filiform papillae, IGFBP-3 was expressed in the core of the connective tissue. At E17, the expression of IGFBP-5 disappeared from the apical region of fungiform, filiform, foliate, and circumvallate papillae, whereas that of IGFBP-2 remained. This finding suggests that IGFBP-5 and -2 function to cause evagination of the epithelium into a raised structure. In the epithelium of trenches of foliate and circumvallate papillae, strong expression of IGFBP-4 was observed at E15 and E17. As previously suggested from a study on postnatal mice (Suzuki et al. J Comp Neurol 2005;482:74-84), IGFBP-4 acts in the epithelial invagination to form the trenches, grooves, or furrows of lingual papillae during development.     

Ultrastructure of vascular capillary of lingual filiform papillae in the mole (Mogella wogura wogura)

Detailed observation of the structure of filiform papillae (FP) and microvasculature of those papillae in Japanese Azuma mole were described. In the anterior and medial regions, FP was cylinder in shape with two processes. In the posterior region, it had a long, sharp conical shape. The microvascular casts showed two types of hairpin-shaped capillary loops on three regions of the tongue. In the anterior and medial regions, the end of the capillary loops were shaped like a spoon. In contrast, in the posterior region, it was knot-like end of capillary loop. Since the shape of capillary loop was more complex in the anterior and medial regions than that in the posterior region, it was speculated that the spoon-like end of capillary loops of the FP in the anterior and medial regions supply nutrients to the filiform papillary cells and may be related to the movement of the tongue during mastication in Japanese Azuma mole.     

Morphological studies of rat lingual filiform papillae

In an attempt to elucidate the functions of three types of filiform papillae in the rat's tongue, corrosive resin casts of the microvessels in the filiform papillae were observed under the scanning electron microscope. The filiform papillae were also examined by light and transmission electron microscopy. The three dimensional architecture of the microvessel loops in the small conical filiform papillae was relatively simple with limited divergence and anastomosis in the papillae, whereas that in the large conical filiform papillae formed a complex network which resulted from repeated divergence and anastomosis. The microvessels in the thready filiform papillae branched several times in the primary papillae and then formed a hairpin-like loop in each of the secondary papillae. Under the light and transmission electron microscope, the small and large conical filiform papillae revealed remarkably similar tissue architectures, with the exception of their sizes. However, these two types of filiform papillae were arranged in quite opposite directions. In the large conical filiform papillae, the epithelium on the anterior side of the papillae lacked a granular layer, whereas the epithelium on the posterior side contained a well-developed granular layer. Based on these findings, we presume that the functions of the three type of filiform papillae are as follows. That of the small conical filiform papillae is to take food efficiently into the oral cavity. That of the large conical filiform papillae is to grind further the food which has been crushed with the teeth in coordination with the palate. The thready filiform papillae might function as a heat-releasing organ and be involved in the control of body temperature.     

Functional and angioarchitectural structure and classification of lingual papillae on the postero-dorsal surface of the beagle dog tongue.

A scanning electron microscopic study was done of the three-dimensional, morphological structure and classification by means of microvascular cast specimens (MVCS) of the filiform (FiP), fungiform (FuP) and circumvallate papillae (CvP) on the postero-centro-peripheral, and conical papillae (CoP) on the posteroperipheral-dorsal surface of the caudal portion of the beagle dog tongue. The characteristics and functional arrangement of each lingual papilla were as follows: the FiP densely and geometrically covered the entire postero-centro-peripheral dorsal surface. The outer structure of the FiP, consisting of both the ascending and descending branches from their tributaries, was a spoon-like capillary micro-network structure with a sharp arrowhead-like top inclined posteriorly. On the other hand, the outer structure of the FuP, appearing sporadically on the oblique lines of the FiP, was of round form consisting of a capillary microvascular network structure. The FuP, consisting of ascending and descending branches similar to the FiP, were distributed sporadically and geometrically on oblique lines in a V-form running from both peripheral sides to postero-central direction on the FiP A group of three CvPs were arranged on oblique lines in a V form from the peripheral to the postero-central region on the postero-dorsal surface. The outer shape of the microvascular network structure of the CvP was a round fence-like structure surrounding the papillary body and the papillary body consisted of an inner semi-spherical microvascular network structure. The CoP densely covered the entire postero-peripheral-dorsal surface. The exterior figure of the conical micro-network structure, consisting of both the ascending and descending branches of the CoP, was a cone-like capillary network structure, and the sharp tops were inclined posteriorly. They were classified into three types: large (L-CoP), medium (M-CoP) and small (S-CoP) according to the morphological characteristics in shape, size and the distributive position. It was conjectured that the FiP play a concentric functionally important role in transporting food and liquid from both sides in a postero-central direction towards the pharynx. And, on the other hand, the FuPs play an assistant role in receiving gustatory sensations from the masticated food and liquid on the central dorsal surface. The CoP play a functionally important role on the postero-peripheral-dorsal surface, in transporting food and liquid towards the pharynx and a complementary role of the CvP is to receive gustatory sensations from masticated food and liquid on the postero-peripheral-dorsal surface of the caudal portion of the beagle dog tongue.     

Morphology of the glomerular nerve endings in the dorsal nasal ligament of the dog

The nasal atrium appears to be an important sensory site in the dog, yet no literature is available concerning its nerve supply. The present paper demonstrates the occurrence of glomerular nerve endings in the canine nasal atrium, using immunohistochemistry for neurofilament protein (NFP) and for glial fibrillary acidic protein (GFAP). Glomerular nerve endings occurred on the perichondrium of the septal and the dorsal lateral nasal cartilages, and their terminal portions were attached with dense collagen fibril strands of the dorsal nasal ligament. The glomerular endings were derived from a thick parent axon which branched repeatedly. Complicated winding nerve fibers gave rise to numerous thin filamentous terminals. Accumulations of GFAP immunoreactive glial cells were also observed. Immunoelectron microscopy for NFP revealed several axon terminals in the glomerular endings which contained numerous neurofilaments and mitochondria and were incompletely covered by Schwann cell sheaths. The glomerular endings in the dog nasal vestibule are suggested to perceive tensional changes in the nasal dorsal ligament caused by the opening of the nostrils and to be involved in the reflex regulating the activity of the nasal muscles.