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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.

We describe the morphological adaptations of the tongue and gastrointestinal tract of the striped sand snake Psammophis sibilans and discuss their functional importance. Using standard histological, histochemical, and scanning electron microscopy techniques, we analyzed 11 adult snakes of both sexes. Our findings showed that the bifurcated non-papillate tongue exhibited chemoreceptive adaptions to squamate foraging behavior. The lingual apex tapered terminally with sensory spines, and the body of the tongue possesses a characteristic central odor–receptor chamber that might serve to trap and retain scent molecules. Furthermore, the intrinsic musculature showed interwoven and well-developed transverse, vertical and longitudinal muscle fibers that control contraction and retraction during probing and flicking. The esophagus displayed highly folded mucosa lined with columnar epithelium with goblet cells. In contrast, the stomach mucosa formed finger-like gastric rugae, encompassing tubular glands with dorsal gastric pits. The intestine is distinct from other vertebrates in lacking the crypts of Lieberkühn in the tunica mucosa and submucosa. The intestine mucosa is mostly arranged in interdigitating villi oriented perpendicular to the luminal surface. We extrapolated subtle variations for both acid and neutral mucopolysaccharides and glycoproteins localization as well as collagen fibers using histochemical analyses. The elaborate histo-morphological and functional adaptation of the tongue and digestive tract plays a pivotal role in foraging and feeding behavior.

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The present study was designed to provide a complete morphological description of the eye of the migratory Garganey duck (Anas querquedula) and its visual adaptation with the different surrounding environmental conditions during its migration journeys using a stereomicroscope, scanning electron microscope (SEM), and light microscope. The current work depends on six adult Garganey ducks that were captured from the area near and on the shores of Edku city. The obtained results revealed that the eye of the migratory Garganey duck has the features of both diurnal and nocturnal birds. The histological examination reveals that the pigmented epithelium of the retina has long prolongations filled with melanin. The cone is the dominant photoreceptor, but simple rods are present. The inner nuclear and ganglion cell layers are thick. SEM examination shows that the arrangement of the collagen fibrils on the external surface was reticular in shape. The radial folds present as pledged structures on the pigmented epithelium covered with circular structures. The main lens body has flat with hexagonal outlines fibers. The edges and surfaces of these hexagonal fibers were studded with protrusions or elevations (balls) and depressions (sockets). The sockets and balls were either rounded or ellipsoid in shape. The balls were more on the edges and the sockets on the surface. In conclusion, our findings indicated a higher degree of functional adaptation between the morphological structure of the eye and the surrounding environmental conditions.