Gross anatomical features of the oropharyngeal cavity of the ostrich (Struthio camelus)

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.

Recessive white plumage color mutation of Japanese quail (Coturnix coturnix japonica) revealed morphological variations in the oropharyngeal roof structures, accompanied by behavioral differences

Genetic background of experimental animals contributes mainly to the variations in the experimental outcomes. Therefore, quails of two lines of plumage color (brown and recessive white) were studied to investigate the impact of plumage color mutations on the morphological structures of the oropharyngeal roof and also on the ingestive behavior and quail performance. Feeding intake and feed conversion ratio were higher in the brown quails, associated with nonsignificant increase of the live body weight and body weight gain. In the recessive white quails, ingestive behaviors revealed significant declines. The roof of the oropharynx roof was significantly longer in the recessive white quails; however, the upper beak was significantly longer and narrower in the brown ones. The length of the palate and pharynx showed nonsignificant increase in the recessive white quails. The median palatine ridge was formed of rostral continuous and caudal interrupted parts, and the lengths of these parts were slightly higher in the recessive white quails, meanwhile the lateral palatine ridge length showed a slight increase in the brown birds. Openings of intraepithelial glands were more numerous in the recessive white quails. The brown quails demonstrated more detectable and larger caudally directed conical shaped palatine and pharyngeal papillae, in addition to more considerable palatine salivary glands openings. The infundibular cleft was significantly wider in the recessive white quails, where its edges were characterized by lack of the pharyngeal papillae. The findings of this study will be beneficial for the breeders during selection the suitable quail lines for meat production purposes.

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.

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.

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.

Relating form to function in the hummingbird feeding apparatus

A complete understanding of the feeding structures is fundamental in order to study how animals survive. Some birds use long and protrusible tongues as the main tool to collect their central caloric source (e.g., woodpeckers and nectarivores). Hummingbirds are the oldest and most diverse clade of nectarivorous vertebrates, being a perfect subject to study tongue specializations. Their tongue functions to intraorally transport arthropods through their long bills and enables them to exploit the nectarivorous niche by collecting small amounts of liquid, therefore it is of vital importance to study its anatomy and structure at various scales. I focused on the portions of the hummingbird tongue that have been shown to be key for understanding their feeding mechanisms. I used histology, transmission and scanning electron microscopy, microCT, and ex-vivo experiments in order to advance the comprehension of the morphology and functioning of the hummingbird feeding apparatus. I found that hummingbird tongues are composed mainly of thin cornified epithelium, lack papillae, and completely fill the internal cast of the rostral oropharyngeal cavity. Understanding this puzzle-piece match between bill and tongue will be essential for the study of intraoral transport of nectar. Likewise, I found that the structural composition and tissue architecture of the tongue groove walls provide the rostral portion of the tongue with elastic properties that are central to the study of tongue-nectar interactions during the feeding process. Detailed studies on hummingbirds set the basis for comparisons with other nectar-feeding birds and contribute to comprehend the natural solutions to collecting liquids in the most efficient way possible.

Morphological Characteristics of the Oropharyngeal Cavity (Tongue, Palate and Laryngeal Entrance) in the Eurasian Coot (Fulica atra, Linnaeus, 1758)

The present study represents the first definitive anatomical description of the oropharyngeal cavity of the coot Fulica atra. For this purpose, the organs of six birds were prepared to examine grossly and by SEM and stereomicroscope. The oval lingual apex had multiple overlapping branched acicular processes on its anterior and lateral border. The lingual apex and body had multiple caudally directed filiform-like papillae. By stereomicroscopy, the lingual root had a characteristic appearance and consisted of four parts. The openings of the anterior glands were present on the dorsal lingual surface of the body, while the projected papillae with wide openings of the posterior glands were present on the dorsal surface of lingual root. There was a row of caudally directed pharyngeal papillae at the caudal border of the laryngeal mound. Grossly, the pharyngeal papillae arrangement took a W-shape, while by stereomicroscopy was observed to be heart shape. The palate was divided into two regions: a small rostral non-papillary and a large caudal papillary region, but the rostral region was characterized by the presence of three longitudinal ridges. The papillary crest had two paramedian longitudinal papillary rows, which continued caudally until the beginning of the third median row. The freely distributed papillae took a caudolateral direction, while the papillae encircling the rostral part of choanal cleft took a caudomedial direction. There was a transverse papillary row between the two parts of choanal cleft. There was a transverse papillary row between the caudal border of the infundibular cleft and oesophagus.

Function-related morphological characteristics and specialized structures of the avian tongue

As a reflection of different life styles and environment, the tongue of vertebrates, which plays a major role in the intake and swallowing of food, displays significant morphological differences. The gross form and microscopic structure of the avian tongue differ greatly according to lifestyle. The avian tongue plays a fundamental role in many functions such as capturing, filtering, sucking and manipulating food in order to compensate absence of subsidiary organs like teeth in the oropharyngeal cavity. Variations in lingual papillae play an important role in feeding of birds, as they represent a structure similar to teeth in the upper and lower beaks and can be used to hold and direct food in the oropharyngeal cavity. Tongues of birds exhibit common as well as varying anatomical characteristics in terms of surface morphology, structure and topographical distribution of lingual papillae as well as distinct specialized structures, epithelial layers, taste buds and lingual glands. This review evaluates the important morphological peculiarities of the tongue in birds, focusing on the relationship between anatomical features and feeding functions.

Gross morphology of rhea oropharyngeal cavity

The rhea (Rhea americana americana) is an american bird belonging to Ratite's family. Studies related to its morphology are still scarce. This study aims to describe the macroscopic structures of the oropharyngeal cavity. Five heads (2 to 6 months old) formalin preserved were anatomically dissected to expose the oropharynx. The oropharynx of the rhea was "bell-shaped" composed by the maxillary and mandibular rhamphotheca. The roof and floor presented two distinct regions different in colour of the mucosa. The rostral region was pale pink contrasting to grey coloured caudal region. The median longitudinal ridge extended rostrally from the apex of the choana to the tip of the beak in the roof and it is clearly more prominent and rigid than the homolog in the floor that appeared thin and stretched merely along the rostral portion of the regio interramalis. The floor was formed by the interramal region, (regio interramalis) tongue and laryngeal mound containing glove-shaped glottis. This study confirmed the basic morphology of the oropharinx of the rhea. However, important morphological information not previously described is highlighted and contradictory information present in the literature is clarified.

Macroscopia e topografia do aparelho digestório de emas (Rhea americana americana)

As emas são aves que pertencem ao grupo das ratitas e juntamente com os avestruzes e emus, são as maiores aves vivas na atualidade. Neste trabalho estudou-se os aspectos macroscópicos do aparelho digestório de emas com o intuito de fornecer informações importantes ao estudo dos hábitos alimentares dessas aves, bem como de sua anatomia. Foram utilizados vinte animais jovens com idade entre dois e seis meses obtidos do Centro de Multiplicação de Animais Silvestres (Cemas), registrado com criador científico sob o nº 1478912. Após dissecação verificou-se que a língua era pequena, disposta no assoalho da cavidade oral, possui forma rombóide e estava inserida pela sua base por um frênulo. O esôfago era um tubo retilíneo de aspecto elástico com fibras longitudinais, sem dilatação, o que confere a ausência do papo. O proventrículo gástrico apresentava formato fusiforme. O ventrículo gástrico possuía formato ligeiramente oval, quando repleto, internamente era recoberto por uma cutícula gástrica espessa. O intestino delgado era formado por três regiões distintas: duodeno, jejuno e íleo. O duodeno possuía coloração cinza claro e apresentava-se curvado em forma de "U". O jejuno era longo e formado por várias alças curtas dispostas uma sobre a outra e possuía coloração verde escuro. O íleo era de cor cinza e continuo com o jejuno. Na linha ventral ao reto e cloaca, este se estendia em sentido cranial, dorsalmente ao duodeno ascendente. O intestino grosso era formado por dois cecos, um direito e um esquerdo, e o cólon-reto contínuo com o íleo e a cloaca. As estruturas que compõem o aparelho digestório de ema assemelham-se com o que preconiza a literatura, com relação à forma e topografia para a maioria das aves, contudo os cecos são bem desenvolvidos e bastante dilatados nas emas.