The present work was aimed to study the gastrointestinal tract in Garganey from the oesophagus to coprodeum by the aid of the gross morphology, scanning electron microscopy and histology. At the level of the thoracic inlet, the oesophagus had a thick part which had numerous tortuous longitudinal folds carried transverse folds on them. Histologically, the thick part had thick epithelium and appeared more folded with more and larger glands. The mucosa of the proventriculus had mucosal folds appeared as a leaf‐like with rounded tips. The openings of the proventriculus glands were projected with papillae on the epithelial surface. The gizzard lined with horizontal layer of cuticle which sent vertical parts of cuticle. The duodenal villi were pentagonal in shape with sharply pointed tips, while the jejunal villi were triangular with rounded ends, and the ileal villi were wide and pentagonal in shape with pointed tips. The mucosa of the duodenum, jejunum and ileum was thrown into villi lined by simple columnar epithelium with goblet cells with difference in the form, length, density and number. The apical points of the duodenal and ileal villi appeared pointed, while the jejunal villi had rounded ends. The jejunal villi were longer and numerous than the duodenal villi, but the ileal villi appeared with different length and less numerous. The mucosa of the caecum had numerous mucous glands which surrounded by circular crypts. The rectal mucosa had longitudinal folds and semilunar and circular crypts. The mucosa of the coprodeum had longitudinal folds surrounded by crypts.

Bagrus Bayad (Forskal, 1775) is a bottom feeder fish feeds on different food items. Its oral cavity anatomy has many types of teeth adapted to the capacity and varieties of feeding. The aim of the present study was to use the gross anatomy and scanning electron microscopy to identify the anatomical characteristic, especially of the teeth and taste buds distributed on the roof and floor of the oropharyngeal cavity. The results clarified that Bagrus Bayad has two types of teeth; curved pointed and blunt teeth of different sizes. The teeth appeared on epithelial protrusions. The pharyngeal region had upper and lower pharyngeal teeth, the upper arranged into two oval prominences while the lower ones arranged into two triangular areas. The higher number of the pointed teeth is prove the carnivorous nature of the Bagrus Bayad. Three types of taste bud (I, II, & III) were found in the oropharyngeal cavity. The tongue present in the floor and free from teeth and characterized by the presence of taste bud type I and II. Many microridges of different arrangement observed on the surface epithelium of oropharyngeal cavity. The upper and lower valve characterized by the microridges, pores and taste buds. The knowledge of the nature of the oropharyngeal cavity of the Bagrus Bayad helps in identifying new and better methods for feeding in aquaculture.

The current work gives concern to study the morphology of the Merluccius merluccius gills by using gross morphology, scanning electron microscopy (SEM), and light microscopy. The findings of the present study revealed that the gill system consisted of four pairs of gill arches which carry the gill filaments on the convex border and gill rakers on the concave border of them. SEM results revealed that the rakers and the spines distribution on the first gill arch differed from that of the other three gill arches on the lateral and medial surfaces. On the surface the gill filaments, there were longitudinal ridges that carried pores of chloride cells and mucous cells. The histological examination revealed that, the gill arch composed of hyaline cartilage that presented in the form of cups. Each cup consisted of central cartilagenous core and peripheral cartilagenous matrix. The gill filaments composed of cartilaginous bar of peripheral cartilaginous matrix and central cartilaginous core extended from the gill arches and covered by an epithelial layers with a few mucous cells permeate it, and chloride cells were straggly in the interlamellar epithelium. Each gill filament carried several leaves like secondary lamellae on both sides of it. The epithelium, which lined the secondary lamellae, composed of epithelial pavement cells, some mucous cells, and pillar cells. K E Y W O R D S gills, light microscopy, Merluccius merluccius, morphology, scanning electron microscopy

The present investigation was prepared to give a complete ultrastructural characterization of the pecten oculi of the diurnal European wild Quail to describe their adaptation habits to the Northern Egyptian coast. Our work declares the first endeavor is the elemental analysis using scanning electron microscopy‐energy dispersive X‐ray (SEM–EDX) to show the migration effect on their eye. The intra‐ocular quadrilateral trapezoid black pigmented plicated type pecten oculi were observed on the postero‐inferior wall of the eyeball with craniocaudal and posterio‐anterior directions along the fetal fissure. The pecten oculi consist of three parts: the basal, body, and apical. The basal part originated behind the optic nerve, forming the slightly elevated border, while the apical part was directed toward the ciliary body. There are 10–11 pleats with interpleat space. The coiled surface refers to numerous capillary vessels. The smooth head of each pleat was kidney‐like, strongly attached to a bridge. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. There are numerous melanosomes and little hyalocytes on the pecteneal pleat's outer surfaces. The thick basal part of each pleat had numerous thick longitudinal microfolds that refer to the numerous blood capillaries attached to the retina as supporting roots. SEM/EDX elemental analysis revealed that carbon is the highest element (half), while oxygen represents about one‐third. In the meantime, the lowest element is the phosphate at the apical part, while the lowest element in the rest is the sulfate. Finally, the pecten oculi are thought to be a reflection of the avian lifestyle and ecological adaptations. Highlights Our work is the first description of the elemental analysis using SEM–EDX to show the migration effect on their eye. The quadrilateral trapezoid black pigmented plicated type pecten oculi were observed on the postero‐inferior wall of the eyeball with cranio‐caudal and posterio‐anterior directions along the fetal fissure. The basal part of the pecten oculi originated behind the optic nerve, forming the slightly elevated border, while the apical part was directed toward the ciliary body. There are 10–11 pleats with interpleat space. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. There are numerous melanosomes and little hyalocytes on the pecteneal pleat's outer surfaces. SEM/EDX elemental analysis revealed that carbon is the highest element (half percent), while oxygen represents about one‐third of the element's percent meanwhile, the lowest element is phosphate at the apical part, while the lowest element in the rest is the sulfate.

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.

The present study represents the first attempts to give a full anatomical comparison of the vascular pigmented pectin oculi of the diurnal activity Anas querquedula and Gallinula chloropus chloropus. For achievement of this work, 10 mature birds from each species were examined under stereo‐ and electron microscope. The pecten oculi of A. querquedula is triangular fan‐like, while in Gallinula c. thin like‐fold. In both examined birds, the pecten oculi located postero‐anteriorly intraocular just adjacent to optic nerve disc and attached to the retina by its base, while the free apex projected into vitreous body. A. querquedula had 14–15 pleats, while Gallinula c. chloropus had 22–24 pleats. In A. querquedula, all pecten pleats connected to each other apically by a connecting bridge. The pecten oculi was plicated type in A. querquedula, but folded type in Gallinula c. chloropus. In A. querquedula, the external surface of the pleats head carried 8–10 transverse ridges, in addition to the external and lateral surface of the pleat body carried numerous round prominences that indicated the presence of numerous afferent and efferent vessels. In both examined birds, there is a retinal elevated fold situated parallel to the slightly elevated basal fold which is clear and thicker in A. querquedula than in Gallinula c. chloropus. In Gallinula c. chloropus, the transverse section shows that the pleats had numerous afferent and efferent vessels capillaries. Statistical analysis comparing the relative measurements of the pecten oculi in the two examined birds showed that there was a significant difference.

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.

The present investigation focused on the morphological features of the intestine of Eurasian common moorhen by the aid of scanning electron microscopy and histological, morphometric, and statistical examinations. The intestinal villi were varied in shape along the intestinal tract; the duodenal villi were elongated and twisted, the jejunal villi were tongue-like, the ileal villi were cuboidal, and the cecal villi were tongue-like and finger-like at the base and body of the cecum. While at the apex of the cecum, it appeared as corrugated longitudinal folds and the rectal villi appeared as columns. The microvilli were present as projections on the surface of villi of the small intestine and the base of the cecum. While at the body and the apex of the cecum, the microvilli appeared as threads and as brush hairs on the rectal villi.The duodenal, jejunal, ileal, cecal, and rectal villi were lined by simple columnar epithelium with goblet cells. The submucosal layer of small intestine consisted of connective tissue fibers along the intestinal tract, but it was absent at the base of the cecum. The tunica musculosa consisted of single longitudinal layer of smooth muscle fibers in the duodenum and rectum. While in the jejunum, ileum, and cecum, it was composed of single circular layer of smooth muscle fibers. The thickness of the tunics differed among the intestinal parts.