Light and scanning electron microscopic features of the tongue in cattle egret

Comparative histological and ultrastructural features of the tongue of the mallard domestic duck, Anas platyrhynchos f. domestica, Anatidae (Linnaeus, 1758) in different two age stages (post-hatching [P2] and adult female) captured from Egypt

The domestic duck is classified as a specialist filter-feeder bird living in the water. These birds also use grazing and pecking as terrestrial feeding methods. The tongues of domestic ducks, similar to those of other Anseriformes, exhibit numerous types and shapes of mechanical papillae that serve a number of purposes when collecting food. The current study attempts to describe the morphological characteristics of the tongue as well as the mechanical papillae's development. In addition, the study aims to determine whether the papillae observed post-hatching (P2) exhibit similar morphology to those found in adult female avian species, as well as to investigate the readiness of the tongue to fulfill its feeding function following hatching. The comprehensive examination of lingual mucosa is examined about the structural modifications necessary for this variety of feeding activities. In this study, the tongues of nine young (P2) and adult female were used. The tongue had three distinct parts: the apex, which had a lingual nail on its ventral surface; the body, which exhibits numerous small and large conical papillae on its lateral sides and a lingual prominence in the caudal region; and the root, which is covered with numerous conical papillae of varying sizes. Conical, filiform, and hair-like mechanical papillae, the three types of food filtration apparatus, are present in both stages. The intraoral transfer involves several structures, including the median groove, lingual combs, and the rostral border of the lingual prominence. The rostral border of the lingual prominence is characterized by distinct rows of conical papillae. The histological analysis demonstrated the presence of both keratinized and nonkeratinized epithelium on different tongue regions. The lingual salivary glands in the rostral and caudal lingual salivary glands exhibit a pronounced periodic acid-Schiff-positive reaction. Additionally, the yellow adipose tissue and sensory receptors, namely the Grandry and Herbst corpuscles, which collectively form the bill-tongue organ that monitors the movement of food. These results conclude the presence of microstructural species-specific alterations in specific tongue areas of domestic ducks' lingual mucosa. These modifications are formed by the filtering mechanism and terrestrial feeding mechanisms, such as grazing or pecking. Following hatching, the tongue of the domestic duck undergoes significant development, primarily in preparation for grazing activities. The anatomical and histological structure of the young (P2) tongue exhibited similarities to that of the adult female domestic duck while also displaying certain variations that could potentially be attributed to the bird's habitat and mode of feeding. RESEARCH HIGHLIGHTS: The results of this study concluded that the domestic duck exhibit a complex tongue structure characterized by the arrangement and morphology of its mechanical papillae, the presence of the lingual prominence with distinctive shape and the lingual comb. These features are believed to be adaptations that enable the duck to actively and efficiently filter food particles from water, serving as its primary feeding mechanism. Additionally, the tongue of domestic ducks is specifically adapted to facilitate various terrestrial activities, such as grazing and pecking. This adaptation is achieved through the presence of conical papillae and a lingual nail. These investigations facilitate our comprehension of both the anatomical and histological characteristics of the domestic duck tongue, as well as enhance our understanding of bird adaptations to various feeding mechanisms.

Morphological examination and scanning electron microscopy of the barn owl's (Tyto alba) tongue

The beak structure changes according to the feeding patterns of birds. Further, the morphological and histological structures of their tongues vary. Therefore, the current study aimed to perform macroanatomical and histological examinations and scanning electron microscopy of the barn owl's (Tylo alba) tongue. Two dead barn owls were brought to the anatomy laboratory and were used as study material. The tongue of the barn owl was long, triangular-shaped with a bifurcated tip. There were no papillae in the anterior 1/3 of the tongue, and the lingual papillae were shaped toward the back. The radix linguae were surrounded by a single row of conical papillae. Irregular thread-like papillae were found on both sides of the tongue. The salivary gland ducts were on the lateral margin of the corpus linguae and the dorsal surface of the radix linguae. The lingual glands were in the lamina propria near the stratified squamous epithelium layer of the tongue. The dorsal surface of the tongue comprised non-keratinized stratified squamous epithelium, and the ventral surface and caudal part of the tongue had keratinized stratified squamous epithelium. Hyaline cartilages were detected in the connective tissue immediately below the non-keratinized stratified squamous epithelium on the dorsal surface of the root of the tongue. The study results can contribute to the current knowledge on the anatomical structure of birds. Further, they can be useful in managing the barn owl when used as companion animals and in research activity.

Morphological and ultrastructural features of the laryngeal mound of Egyptian Cattle Egret (Bubulcus ibis, Linnaeus, 1758)

Background

According to our acknowledgment this is the first full anatomical description of the studied laryngeal mound of the Egyptian Cattle Egret (Bubulcus ibis, Linnaeus, 1758). This study was obtained with the aid of scanning electron microscopy (SEM) and histological techniques. Heads of ten healthy adult male Egyptian cattle egrets were used in this study.

Results

The laryngeal mound (Mons laryngealis) was a pear-shaped musculoskeletal elevation. It represented 20.55 and 67.87% of the total length of the oropharyngeal floor and the pharyngeal floor, respectively. By SEM view, the lateral aspect of the caudal third of the laryngeal mound had a serrated mucosal appearance, forming of 6–7 finger-like projections. Furthermore, the terminal part of the laryngeal mound (except the middle part) was bordered a transverse row of pyramidal-shaped papillae, which demarcated from the esophagus. Histologically, laryngeal salivary glands termed (cricoarytenoid salivary glands) of the laryngeal mound were simple tubular type and were arranged in one row within the lamina propria connective tissue close to the lamina epithelialis. Those glands were surrounded by abundant aggregation of lymphocytes, extended overlying the surface lining epithelium. The glottis within the laryngeal mound was supported by hyaline cartilages; dorsally by paired arytenoid cartilages, ventrolaterally by cricoid cartilage, and caudodorsally by procricoid cartilage. Two groups of intrinsic laryngeal skeletal muscles have connected the cartilages. The glandular epithelium of the laryngeal salivary glands and chondrocytes of the laryngeal cartilages showed strongly positive alcian blue reaction.

Conclusions

The laryngeal mound shows certain features that are unique as an adaptation to lifestyles and bird’s habitat.

Ultrastructural adaptation of the oropharyngeal cavity of the Eurasian common moorhen (Gallinula chloropus chloropus): Specific adaptive dietary implications

The present investigation represents the first morphological description of the oropharyngeal cavity of Eurasian common moorhen. Nine oropharyngeal cavities were examined grossly and by stereomicroscope and scanning electron microscopic (SEM) observations. The tongue had a rounded apex with multiple acicular processes on its rostral and lateral borders. The dorsal lingual surface of the apex and body had a median sulcus. The papillary crest carried four caudally directed triangular conical papillae on its median part and four triangular conical papillae on each lateral part. The filiform papillary system; small papillae on apex and long papillae on the rostral part of the body while broad papillae on the caudal part of the body. The lingual root had a special appearance by presence of three areas: mucosal fossa, two lateral ridges, and rhomboidal elevated central part. The caudal border of the mound carried heart-shaped pharyngeal papillae that possessed three papillary rows. The palate had a median palatine ridge rostrally that surrounded by two lateral palatine ridges. The choanae had two equal parts: rostral tapering and wide caudal. The rostral tapering choanal part was surrounded by two longitudinal rows of caudally directed conical papillae, one on each side. There was a single transverse row of conical papillae on each side of the caudal part of the rostral tapering choanal part. The caudal wide choanal part did not encircle by any papillae. Our conclusion exhibited unique structural and functional specifications of the oropharyngeal cavity with the tongue that evident with nutritional behavior.

Posthatching ultrastructural development of the oropharyngeal cavity roof in five age-stages of Coturnix coturnix (Linnaeus, 1758)

Recent literature has demonstrated only adult avian palate, albeit there has been only limited focus on the postnatal development of the avian oropharyngeal cavity roof. Hence, the current investigation was designed to obtain the full ultrastructure postnatal description of the oropharyngeal roof during the five developmental age-stages of Coturnix coturnix by employing assessments using gross morphometric analysis and stero and scanning electron microscopy. The elongated triangular oropharyngeal roof has a spoonful rounded beak tip. The palate region is subdivided into the rostral ridged area and the choanal area. The palate has eight longitudinal palatine ridges (seven nonpapillated and one papillated median) and four transverse papillary rows (one slightly oblique row and three transverse papillary crests). The median palatine ridge continuous caudally and is then divided into three ridges: one median and two paramedian ridges (forming the lateral boundaries of the choanal field). The choanal field had three regions (rostral, middle, and caudal). The finger-like projection papillary region has five papillae. The choanal cleft has two unequal parts (rostral and caudal). The rostral nonpapillated short choanal part is subdivided by transverse papillary row into rostral narrow straight and caudal diamond portions. The caudal wide papillated choanal part is further divided by a second transverse crest into rostral long (encircled by interdigitated papillae) and caudal short wider part (not encircled by interdigitated papillae). The infundibular cleft is not bordered by any papillae, while the pharyngeal region has numerous papillae and openings of the salivary glands. Moreover, the morphometric analysis revealed a higher value with increasing age for all dimensions. Our findings indicated a higher degree of functional adaptation between the five developmental age stages of quail. Our observations suggest that adaptations such as these may increase the efficiency of food prehension with increasing age.

Ultrastructural and histological descriptions of the oropharyngeal cavity of the rock pigeon Columba livia dakhlae with special refer to its adaptive dietary adaptations

The current investigation gave a full ultrastructural and histological description of the oropharyngeal cavity of the rock-pigeon Columba livia dakhlae. Our study carried on 10 heads of adult rock pigeons by gross, scanning, and light microscopic examination, in addition to the immunohistochemical analysis of the cytokeratin of the dorsal surface mucosa epithelium and the proliferating cell nuclear antigen expression (PCNA) immunoreactivity. The pointed apex of the elongated tongue covered rostrally and laterally with numerous caudally directed scales-like papillae. The dorsal surface of the apex and body was covered with numerous caudally directed scales-like filiform papillae. The U-shaped transverse papillary crest carried caudally directed pointed triangular conical papillae with two giant papillae. The elevated caudal area of the lingual body contains little numbers of the opening of the lingual gland. The laryngeal mound is divided into two symmetrical halves by rostral fissure and caudal laryngeal fissure into the right and left half. There were four palatine ridges: two lateral, middle, and median ridges. The choanal field bounded by the two lateral palatine ridges and containing the median choanae. The rostral part of the palatine cleft bounded laterally by a line of the small caudally directed conical papillae, while the caudal part was free from these papillae. There was a little number of taste buds in the palate. The high magnification of the rostral part of the beak is covered with directed rods-like projections. In conclusion, the obtained results described the adaptations of the tongue and its belonged structures with the feeding demand of the rock-pigeon.

Biological Aspects of the Tongue and Oropharyngeal Cavity of the Eurasian Collared Dove (Streptopelia decaocto, Columbiformes, Columbidae): Anatomical, Histochemical, and Ultrastructure Study

We characterized the morphological and anatomical adaptations of the lingual microstructures of the Eurasian collared dove and discussed their implications for its dietary niche. We analyzed tongues of nine S. decaocto using histological, histochemical, stereomicroscopic, and scanning electron microscopic techniques. Our findings showed that the tongue is relatively short with a tapered apex that carries a terminal lingual nail. However, the lingual body has median scales and is bordered laterally by filiform papillae. Further, the tongue body bears a distinctive papillary crest. The tongue root is nonpapillate and infiltered with orifices of the posterior salivary glands. The bulky laryngeal mound has a circular glottic fissure, carrying a single row of papillae at the rear edge. Concurrently, our histological and histochemical findings demonstrate that the tongue has taste buds, anterior and posterior salivary glands, along with an elongated entoglossum that extends from lingual apex to root. Besides, ovoid and globular mucous glands displayed intense alcianophilic reactions. More substantially, the palate is made up of three palatine ridges with a caudal choanal cleft that was bounded by two rows of palatine papillae. Our data indicate multiple and novel structural variations for the lingual and palatal sculptures coopted for their feeding style.

Posthatching developmental studies on the tongue and laryngeal entrance of the common quail (Coturnix coturnix, Linnaeus, 1758) in different five age-stages

The present study represents the first trial to characterize the ultrastructural of five ages of Coturnix coturnix. Lingual nail had membrane that differ in number among five studied ages. Filiform papillary system had four caudally directed papillae types; small (apex, rostral, and median part of body in 1 day, body in 10 and 20 days), long (apex and rostral part of body in 10 days, tip and two lateral area in 20, 30, 40-days, lateral border in 1 and 10 days, two lateral area of body in 40 days), broad (median area of body in 20, 30, 40 days). Scales on the ventral surface of apex, mound. Lingual sulci on the apex and body without reaching tip in 10, 20, 30, 40-days while, in 1 day the body had ridge caudally. Three papillae on posterior part of lateral border of body. W-shape crest had papillae on its median part while, its lateral part had two giant papillae on each side. Dorsal giant papillae terminated caudally with six processes, while ventral papillae terminated caudally with three processes. The unique root appearance, at 1 day had four papillae while in 10-day, it had one papilla however in 20, 30, 40 days, it had T-shaped ridge. Mound had one longitudinal row on each side of cleft and two transverse papillary rows at its caudal border and additional row at 40-days. Our findings exposed unique structural and functional characterizations of lingual and laryngeal entrance that reflected with feeding behavior.

Gross morphological, histological and scanning electron specifications of the oropharyngeal cavity of the hooded crow (Corvus cornix pallescens)

The present study was carried out on the oropharyngeal cavity of the hooded crow to investigate the gross and microscopic structures via gross anatomy, light microscopy and scanning electron microscopy (SEM). The gross anatomy clarified the elongated triangular shape of the oropharyngeal cavity with a non-protruding tongue with a bifid apex. The lingual body contained median groove rostrally and separated caudally from the root by a transverse papillary crest. The laryngeal mound located posterior to the lingual root, contained midline laryngeal cleft and bounded caudally by a transverse row of pharyngeal papillae. The palate contained choanal cleft rostrally and infundibular slit caudally in addition to five palatine ridges. By light microscopy, the dorsal lingual epithelium was highly keratinised stratified squamous with a lingual nail in the most rostral part of the apex. Then, the thickness of the keratin layer decreased caudally, while in the ventral surface, the lining epithelium became non-keratinised. The entoglossum supported the lingual body and root, but not extended to the apex. The lining epithelium of the palate was also keratinised stratified squamous and became none-keratinised at the oral side of the choanal cleft. There were numerous lobules of polystomatic salivary glands in the lingual root and the palate. SEM revealed the arrangement of different types of papillae covering both the floor and the roof of the oropharynx besides numerous openings of salivary glands in the lingual root, laryngeal mound and the palate. These findings reflect the functional relationship of the oropharyngeal cavity of the hooded crow during feeding.

Surface ultrastructural descriptions of the oropharyngeal cavity of Anas querquedula

The current work considers the first anatomical description of oropharyngeal cavity of Garganey, which was performed on eight heads with the help of scanning electron microscopy (SEM). The round apex of elongated tongue has anterior spatula-like named lingual nail. SEM of dorsal surface of lingual nail carry microtubercles and micropores on its rostral part, while its caudal part carry numerous microridges and micropores, while lateral apical surface only without lingual nail carrying filiform papillae, but its ventral surface carry exfoliated scales-like projections. Lateral lingual tip carries numerous laterally directed hairs-like structures. Rostral part of body carry region of small conical papillae in between them small hairs-like papillae on its lateral surface. Middle part of body carry lingual comb on its dorsal surface, while its lateral surfaces carry region of small conical papillae in between them hairs-like papillae in addition to filiform papillae, and large conical with small filiform papillae begin to appear laterally to the heads of lingual comb. Lateral surface of lingual prominence carry region of large conical and small filiform papillae on its rostral part, while its caudal part occupied by laterally situated spinated border from the root. Lingual root has two triangular smooth middle and spinated lateral and caudal. Laryngeal entrance divided into papillary and nonpapillary regions. Roof of oropharyngeal cavity divided into lamellar and papillary regions. Choanal cleft divided into rostral narrow ¼ and wide caudal ¾ parts. In conclusion, feeding process depend on the filter feeding mechanism that performed by the help of lateral situated papillae with lingual prominence.

Gross morphological and ultrastructural characterization of the oropharyngeal cavity of the Eurasian hoopoe captured from Egypt

The present study aimed to give full morphological insight into the oropharyngeal cavity of Eurasian hoopoe at the level of gross morphology in addition to ultrastructural inspection including light- and scanning electron microscopy. The oropharyngeal cavity has a triangular appearance with a very long rostrally located beak, helping the bird achieve its feeding mechanism. The floor of the oropharyngeal cavity is divided into three parts; a pre-lingual part with a pre-lingual fold, a lingual part containing a rudimentary triangular tongue, and a laryngeal part, which contains a small elevated laryngeal mound. There are four giant papillae and numerous openings of lingual salivary glands on the root. The roof is divided into the pre-choanal and the choanal region. The pre-choanal region has two parallel palatine ridges, while the choanal region had an ovoid-shaped choanal cleft rostrally, followed caudally by a narrow infundibular slit. The mechanical papillae on the roof are arranged in two rows directed caudally; one row is located on the free border of rostral half of the choanal cleft, while the other row is located between the pharynx cavity and the esophagus. The histological study showed that the tongue was covered dorsally and ventrally by keratinized stratified squamous epithelium and supported centrally by entoglossum, which extends from the root until the rostral tip of the tongue. The entoglossum was mainly cartilaginous rostrally in the apex and ossified caudally in the lingual body and root. Numerous mucous glands scattered in the sub mucosa of the lingual root as well as in the palatine region convey their secretions to the surface through a duct guarded by diffuse lymphocytic infiltration.

Anatomical investigations of the tongue and laryngeal entrance of the Egyptian laughing dove Spilopelia senegalensis aegyptiaca in Egypt

In the present work, the first full anatomical description of the tongue and laryngeal entrance of the Egyptian laughing dove Spilopelia senegalensis aegyptiaca, which was obtained with the aid of scanning electron microscopy (SEM) and histological techniques, is provided. The lingual apex was rounded and the cranially convex papillary crest exhibited a transverse papillary row, in addition to another row consisting of two giant papillae. Papillae were not observed on the elevated, triangular laryngeal mound except for the glottic opening, which was bounded by two lateral elevated borders that presented a row of small papillae. Two fissures occurred on the laryngeal mound: a rostral fissure at the rostral border of the laryngeal mound, and a caudal fissure that occurred caudally to the glottic opening and continued caudally as the laryngeal fissure. SEM analysis showed filiform papillae on the dorsal surface of the apex and body, and indicated that each giant papilla was long with a pointed apex and exhibited one or two secondary papillae on its surface. The dorsal surface of the lingual root exhibited numerous openings of the lingual salivary glands. The caudal part of the laryngeal mound presented numerous openings of the laryngeal salivary glands. Histologically, the dorsal surface of the anterior and middle lingual part was covered with a thick and stratified squamous epithelium. The anterior and middle lingual part presented entoglossum cartilaginous ossification of the entoglossal bone, which had numerous chondrocytes lodged within the lacunae of the entoglossum. The lingual glands appeared in the middle and caudal lingual part.

Surface ultrastructural (SEM) characteristics of oropharyngeal cavity of house sparrow (Passer domesticus)

The focus of the present study is to provide a full morphological description of the oropharyngeal cavity of the house sparrow. The head of six birds was prepared for gross examination and by stereo and electron microscopy. The bifid lingual apex has multiple long, rostrally directed needle-like processes. The lateral border of the apex carries rostromedially directed needle-like processes. The dorsal lingual surface of the apex and body carries numerous caudomedially directed filiform papillae and many orifices of lingual salivary glands. The lingual body is divided into two parts: rostral and caudal. The caudal part is divided into two laterally elevated regions by a median groove, while the rostral part is bounded laterally by a rostrodorsally directed papillary row, which on SEM is formed from two rows. On SEM, the lingual root has many orifices of posterior salivary glands. The pharyngeal papillary row is located at the caudal border of the laryngeal mound, but this single papillary row is formed from two rows at SEM magnification. The laryngeal cleft continues caudally as a laryngeal fissure bounded by two longitudinal rows of caudally directed papillae; at high SEM magnification, this fissure is divided into two halves by a median ridge which carries caudally directed papillae on its posterior part. The choanal cleft proceeds rostrally by the median tubercle. There are a small number of orifices of palatine salivary glands. The morphological characters of the oropharyngeal cavity of the sparrow confirm its adaptation to surrounding environmental conditions and available food particles.