Pecten Oculi Research Articles

Ultrastructural and SEM-EDX Analysis Characterizations of the Pecten Oculi of the Eurasian Stone-Curlew (Burhinus oedicnemus): New Insights to Its Migratory Adaptations With Northern Egyptian Coast.

Our study represents the first attempts to describe the ultrastructure features in addition to SEM-EDX analysis of the pecten oculi of the nocturnal, visually active Eurasian stone-curlew. The present study was carried out on 10 normal pecten oculi from the migrant Eurasian stone-curlew (Burhinus oedicnemus) that was captured from the Northern Egyptian coast, Edku Lake, Edku, Behera, Egypt. The intraocular folded quadrilateral fan black pecten oculi was observed on the posteroinferior wall of the eyeball. The pecten oculi had 18-20 pleats, with narrow spaces in-between. Our SEM findings showed a tortuous, coiled pecteneal surface due to numerous blood capillaries. The apical part was oriented toward the ciliary body, but the basal part was derived from the retina, just behind the optic nerve. The outer pleat surfaces are covered by the vitreopecteneal limiting membrane, which carries numerous hyalocyte cells on the outer pleat surface. The transverse sections revealed numerous blood capillaries surrounded by numerous melanin granules. Each basal part was surrounded by a thin, elevated ridge. Our SEM-EDX analysis revealed that carbon is the highest (half percent), oxygen represents about one-third, and nitrogen is one-fifth percent of all elements. The lowest elements are sulfate at the apical part and phosphorus in the middle and basal parts. In conclusion, our findings reveal that the number of pecteneal pleats is related to the nocturnal active visual pattern and the lifestyle of this migratory bird.

Pecten oculi of kestrel (Falco tinnunculus rupicolaeformes) and little owl (Athene noctua glaux): Scanning electron microscopy and histology with unique insights into SEM-EDX elemental analysis.

There is scanty data about the comparative morphological features between the pecten oculi of two carnivorous birds with different visual active clock hours: the diurnal common kestrel and the nocturnal little owl. This study illustrated the comparative gross, scanning electron microscopy, and histological characteristics between pecten oculi of kestrel and little owl. This study first attempts to describe the scanning electron microscopy-energy dispersive x-ray (SEM-EDX) elemental analysis at the parts (apex, middle, and base) of the pecten oculi of these two birds. The present study results observed the same position, origin, directions, parts, convoluted outer pleat surfaces, and SEM-EDX elemental analysis, but there were some minor variations due to the different visual active clock hours. These minor variations were summarized in the following points: pleat number (21-23 in the kestrel and 10-11 in the owl), shape (fan rhomboid in the kestrel and accordion in the owl), inter-pleat spaces (wider in the kestrel than in the owl), pigmentations (highly black pigmented in the owl than in the kestrel), hyalocyte cell aggregations (highest in the middle and dwindling at the apex and base in the kestrel, while highest in the middle and base and dwindling at the apex in the owl), and SEM-EDX elemental analysis percentage. SEM/EDX elemental analysis confirmed the presence of oxygen (the highest one), carbon, nitrogen (the second one), nitrogen (the third one), and aluminum (the lowest one) in varying percentages within the pecten oculi; these findings contribute to our understanding of its structural, adaptations with different visual active clock hours, and functional characteristics. RESEARCH HIGHLIGHTS: This study compared the pecten oculi of two carnivorous birds with different visual active clock hours: the diurnal common kestrel and the nocturnal little owl. Anatomically, the characteristic features were similar in both the birds, but some minor variations were observed adapted to their visual active clock hours. The pecten oculi of both birds were analyzed using SEM-EDX for elemental analysis, and it revealed that oxygen was the highest elemental concentration, followed by carbon and nitrogen. Aluminum concentrations were small as per SEM-EDX analysis. The study suggested that the pecten oculi of these birds are related to their active visual clocks and adaptive nutritional mechanisms.

Macroscopic and microscopic comparison of pecten oculi in different avian species.

The current study aims to present differences between the pecten oculi of different avian species through morphologic, macroscopic, light, and electron microscopic examinations. The study is a comprehensive research on seven avian species (sparrowhawk, hawk, magpie, swan, heron, pheasant, duck). The right eyes of the animals utilized in the study were removed for light microscopic examination, whereas their left eyes were removed for electron microscopic and macroscopic examinations. Morphometric analyses, as well as stereo and light microscopic measurements, were carried out on the pecten oculi of the animals. Given all these data, it was determined that the height of the pecten oculi did not differ among the species in the study; however, the pecten oculi were larger in birds with the highest value compared to the other species in the macroscopic measurements. Also, the pecten oculi vessels were larger, and the number of melanocytes was higher in keen eyesight, raptor, and migratory birds with large bulbus oculi. All these data suggest that the pecten oculi not only supplies nutrient to the retina but also contributes to sharp vision during migration and hunting, UV absorption from sunlight, as well as preservation of intraocular equilibrium.

The pecten oculi comparison of the different bird species

The pecten oculi is a unique and highly specialized structure found in the eyes of birds. It is a thin, folded, fan-like membrane that extends from the optic nerve region into the vitreous fluid of the eyeball. This membrane is primarily composed of pigment cells, an extensive network of blood vessels, and a thick basal lamina. The pecten's main function is to supply nutrients and oxygen to the retina, maintain the internal eye temperature, and support sharp vision, especially during activities such as migration and hunting. The number of folds in the pecten varies between diurnal and nocturnal birds, with diurnal birds generally having larger and more complex pecten structures. The pigmentation of the pecten, especially at the apical and peripheral regions, plays a role in protecting the blood vessels from UV radiation and oxygen radicals. Different bird species exhibit variations in the number, size, and thickness of pecten folds, reflecting their specific visual requirements. For example, species like the emu have a more primitive, pleated pecten, while birds like the seagull and quail have a greater number of folds and capillaries. Additionally, the presence of melanocytes and their interactions with capillaries and blood vessels contribute to the pecten's structural integrity. The study of the pecten oculi's histology reveals that it is essential for the bird's visual health and can be linked to their lifestyle and environmental conditions. The structure and size of the pecten are tailored to the bird's daily activities, with diurnal birds having larger and more complex pecten structures compared to their nocturnal counterparts. This specialized organ's morphology and vascularization are crucial for delivering nutrients to the retina and protecting it from UV radiation. In summary, the pecten oculi is a remarkable anatomical feature in the avian eye, and its structure and function are closely related to the lifestyle and visual requirements of different bird species. This study provides valuable insights into the diverse adaptations of the pecten across bird species and its significance in maintaining avian visual health.

Biological features of the pecten oculi of the European wild quail (Coturnix coturnix): Adaptative habits to Northern Egyptian coast with novel vision to its SEM–EDX analysis

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.

Gross, ultrastructural, and histological characterizations of pecten oculi of the glossy ibis (Plegadis falcinellus): New insights into its scanning electron microscope-energy dispersive X-ray analysis.

The current study shows the first attempts to clarify the gross, ultrastructure, and histological properties of the pecten oculi of the diurnal, visually active glossy ibis, as well as scanning electron microscope-energy dispersive X-ray (SEM-EDX) image analysis (Plegadis falcinellus). The pecten oculi was found on the eyeball's posteroinferior wall, adjacent to the optic nerve in both the craniocaudal and posterio-anterior directions. The plicated quadrilateral black pigmented pecten oculi consisted of a base, 10-12 pleats, and an apex. The base was joined by an elevated ridge and derived from the non-vascular retina, while the apex was not a fused part and was found neighboring the gelatinous vitreous body. The limited interpleat spaces were somewhat wider at the base of the pecten oculi. The outer surface of each highly vascular pecten pleat revealed a tortious coiled formation due to the existence of a considerable number of capillary vessels. The outer pleat surfaces had a vitreopecteneal limiting membrane that segregated the pecten pleats from the vitreous body. The high SEM magnification revealed that there are considerable plentiful hyalocyte cells on the outer surface of the pleats. The SEM-EDX analysis of the elementary formatting of the pecten oculi (at apex, middle, and base) clarified that the carbon represents the highest and a half percent. Furthermore, oxygen represents one-third of all elemental composition in the three regions, while the lowest percentage is calcium. Finally, the pecten oculi characterizations of this migratory bird on the Northern Egyptian shore were associated with their adaptive dietary strategies.

In Vivo Imaging of Retinal and Choroidal Morphology and Vascular Plexuses of Vertebrates Using Swept-Source Optical Coherence Tomography.

PurposeTo perform in vivo evaluation of the structural morphology and vascular plexuses of the neurosensory retina and choroid across vertebrate species using swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA) imaging.MethodsA custom-built SS-OCT system with an incorporated flexible imaging arm was used to acquire the three-dimensional (3D) retinal OCT and vascular OCTA data of five different vertebrates: a mouse (C57BL/6J), a rat (Long Evans), a gray short-tailed opossum (Monodelphis domestica), a white sturgeon (Acipenser transmontanus), and a great horned owl (Bubo virginianus).ResultsIn vivo structural morphology of the retina and choroid, as well as en face OCTA images of retinal and choroidal vasculature of all species were generated. The retinal morphology and vascular plexuses were similar between rat and mouse, whereas distinct choroidal and paired superficial vessels were observed in the opossum retina. The retinal and vascular structure of the sturgeon, as well as the pecten oculi and overlying the avascular and choroidal vasculature in the owl retina are reported in vivo.ConclusionsA high-quality two-dimensional and 3D in vivo visualization of the retinal structures and en face visualization of the retina and choroidal vascular plexus of vertebrates was possible. Our studies affirm that SS-OCT and SS-OCTA are viable methods for evaluating the in vivo retinal and choroidal structure across terrestrial, aquatic, and aerial vertebrates.Translational RelevanceIn vivo characterization of retinal morphology and vasculature plexus of multiple species using SS-OCT and SS-OCTA imaging can increase the pool of species available as models of human retinal diseases.

Ultrastructural characterizations of the pecten oculi of the common ostrich (Struthio camelus): New insight to scanning electron microscope-energy dispersive X-ray analysis.

The current observation was designed to give a complete ultrastructural description of the pecten oculi of the common ostrich (Struthio camelus). Moreover, this study represents the first attempt to measurements the elements composition of the pecten oculi using scanning electron microscope-energy dispersive X-ray (SEM-EDX) at three regions (apical, body, and basal). To accomplish this study, eight ostrich were examined grossly and under the electron microscope. The vaned-shaped pecten oculi consisted of three regions (apex, body, and base) with 24-25 plates. The pecten oculi was located postero-anteriorly near to the optic nerve disc that was attached by their bases to the retina forming a slightly elevated basal border joining the bases of all pleats, while the apex was linked in a circular bridge. The pleats are separated from each other by the inter-pleat spaces that are very clear at the base and nearly not observed at the apical part. The outer pleat's surface carried numerous prominences that pointed to the existence of numerous afferent and efferent pecteneal blood capillaries vessels. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. Our findings concluded that, the high number of thick pecteneal pleats was related to the diurnal activity of the common ostrich. SEM-EDX shows that the carbon percentage in the three regions is the highest that representing about half of all elements, while the oxygen percent is about one-third; meanwhile, the lowest percentage is the sulfate at the apical region, and the calcium at the body and basal regions.

Morphological and Ultrastructural Studies of Pecten in the Eurasian Tree Sparrow.

We studied the fine histological structures of pecten oculi of the Eurasian tree sparrow using various microscopy techniques. The pecten of the tree sparrow was found to be of a pleated type comprising of pleats, bridges, and base. The light microscopic study revealed further that the pleats consist of capillaries of varying sizes, blood vessels, and numerous pigmented cells that give them a black color. Histochemical studies of pecten showed a large deposition of lipid droplets, which were more abundant in the basal area. The transmission electron microscopy displayed capillaries and blood vessels that remain surrounded by a thick fibrous basal membrane. They are formed of endothelial cells having a large lumen and abluminal area with microfolds. Interstitial spaces were found filled with rounded melanocytes, electron-dense pigment granules, and mitochondria. Observations under the scanning electron microscope revealed the presence of a dense vascular network of capillaries and vessels. In addition, large hyalocytes were also observed on the surface of the pleats. The above observations suggest that the histological structure of the pecten of the tree sparrow resembles those present in the pecten of other diurnal birds. However, further investigation is required to ascertain its functional role in birds.

Ultrastructural studies of the pecten oculi of the Garganey (Anas querquedula, Linnaeus 1758) and the Eurasian common moorhen (Gallinula chloropus chloropus, Linnaeus 1758).

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.

Foveal shape, ultrastructure and photoreceptor composition in yellow-legged gull, Larus michahellis (Naumann, 1840)

The anatomical and histological features of the foveae in a gull, Larus michahellis, were investigated combining immunofluorescence and transmission electron microscopy. In an area of higher acuity, which extends in a band across the field of view, a central convexiclivate deep fovea was observed near of the pecten oculi. Moreover, a shallow fovea was present in the dorsonasal region. The central deep fovea was characterized by a remarkably and well-excavated pit containing extremely thin cones and a radial displacement of the cone axons and inner retinal layers. Immunofluorescence demonstrated the absence of rods and the presence of violet and green/red sensitive cone opsins. Ultrastructural analyses confirmed the lack of double cones, and specialized Muller cell processes forming a network that stabilizes the foveal structure. This deep central fovea, which provides the highest resolution and colour discrimination, may be used for monocular sideways vision of distant objects and a binocular fixation. The dorsonasal fovea was shallower and all retinal layers were present at the pit. This fovea showed the same composition of photoreceptors than central fovea and could be implied in magnification of a wide monocular part of the retinal image. The bifoveate condition of yellow-legged gull retina would allow the formation of three separate and distinct visual fields: two wide lateral monocular fields mediated by the dorsonasal and the central foveae, and a small binocular field mediated by the central deep fovea depending on ocular movements.

Macroanatomic, light and scanning electron microscopic structure of the pecten oculi in northern bald ibis (Geronticus eremita).

Eyes are the most primarily required sensory organs during the migration of migratory birds and Northern Bald Ibises (Geronticus eremita) are known to make long migrations. This study examined for the first time the structure of pecten oculi in northern bald ibises by using macroscopic anatomy as well as light and electron microscopic methods. In the study 20 eye globes from 10 adult bald ibises were used. The pecten was of pleated type. As in most bird species, it was located on the optic nerve head and projects into the vitreous from the optic nerve head. The wider basal part was observed to attached to retina and its free apical part was found in camera vitrea bulbi embedded in corpus vitreum. The pecten had 13-14 accordion like pleats lying between the basal and apical parts. In addition to arterial and venous vessels, numerous capillary vessels as well as melanocytes were observed within each pleat. The bridge binding the pleats at the apical part showed a stronger pigmentation compared to other parts of the pecten. The results of the study indicated that the general morphology of pecten oculi in northern bald ibises which is a migratory bird species were similar to that in other diurnal bird species.

Light and electron microscopic studies on the pecten oculi showing blood-retina barrier properties in Turkey's native Gerze chicken.

The pecten oculi is a highly vascularized and pigmented organ that projects from the optic disc into the vitreous body in the avian eye. In this study, the pecten oculi of Turkey's native Gerze chicken was examined by light and scanning electron microscopy. Furthermore, the localization of some adherens junction components (E-cadherin and pan-cadherin) in intact vessels of the blood-retina barrier was investigated by immunohistochemistry. In the Gerze chicken, the pecten oculi was a thin structure, which was located over the head of the discus nervi optici and projected from the retina into the corpus vitreum. The pecten oculi consisted of 18-21 highly vascularized pleats, joined apically by a bridge and resembled an accordion in appearance. Hyalocytes and melanocytes were observed around the small and large vessels. The morphometric data of the pecten oculi showed that there were no statistical differences in terms of sex. The immunohistochemical analysis of the pecten oculi, which is used as a model for the investigation of the formation and maturation of the barrier properties in the central nervous system, revealed cytoplasmic E-cadherin and pan-cadherin immunoreactivity in the endothelial cells of the small, large and capillary vessels. These observations suggest that while the morphological and histological structure of the Gerze chicken's pecten oculi was generally similar to that of other diurnal domestic birds, the pecten oculi, a model system for vascular differentiation and the blood-retina barrier, expressed different cadherins.

Comparative Anatomical and Histological Study of the pecten oculi in three species of birds that differ in their nutrition

The present study dealt with the anatomical and histological structure of pecten oculi in three species of birds that differ in their nutrition, these birds were Accipiter nisus, Sturnus vulgaris and Taeniopygia guttata, by using compound light microscope and five different histological stains. The result showed that, pecten oculi was in the three species of pleated type and consisted of 17 folds in Accipiter nisus, 26 folds in Sturnus vulgaris and 19 folds in Taeniopygia guttata, these folds were vary in their thickness, as they were thicker in Accipiter nisus than the other two species. The results also showed that the pecten oculi folds of the three species contains three types of blood vessels: large size, medium size and blood capillaries. The three types of vessels were differ in their diameter and their distribution between the folds of pecten oculi with in one speceis as well as they differ in the other three species. Pecten oculi also contains pigment cells as well as peripheral cells, it ends in the three birds speceis with a structure known as the bridge which is consist of connective tissue and dense pigment cells. The bridge is rich in blood vessels of different sizes. The present study concluded that the pecten oculi differ in components and anatomical features in different speceis of birds.

A comparative ultrastructural study of the pecten oculi in adult, juvenile, and nestling yellow‐legged gulls, Larus michahellis (Naumann, 1840)

This study aimed at examining the histological structure of the pecten oculi in the adult yellow-legged gull, Larus michahellis, and at two moments of postnatal development: during the posthatch (nestling) and juvenile periods. Particular attention was paid to differences in the diameter of vessels, the thickness of the basement membrane, and ultrastructural features of endothelial and pigmented stromal cells. Capillary endothelial cells displayed numerous microvillous-like folds projecting from their internal and external surfaces. Intercellular spaces between capillaries were occupied by pigmented stromal cells. The ultrastructure of pecten oculi underwent noticeable changes during postnatal development. The examination of the capillaries in nestlings, juveniles, and adults revealed that the formation process of vessels and pigmented stromal cells did not complete itself in the posthaching phase. The prominent feature of endothelial cells of capillaries in nestlings was that the microvilli were longer than in juvenile and adult cells, and the capillary lumen was therefore reduced. In this sense, their pigmented stromal cells showed fewer melanosomes, lacked intercellular spaces, and cellular junctions could still be observed. These results provide evidence that the pecten oculi during the posthatching phase maintains immature morphological features consistent with a role of pigmented stromal cells in the blood-retina barrier.

Gross, histochemical and electron microscopical characterization of the Pecten oculi of Baladi ducks (Anas boschas domesticus).

Objective:As pecten oculi had great functional significances for ornithology, pecten oculi of Baladi duck was well-deserving of intensive morphological study. So, the aim of this study was to throw light on some anatomical and histological formation of the pecten oculi of Baladi ducks as well as use of scanning electron microscopy.Materials and Methods:Twenty eyeballs of 10 adult Baladi ducks were used to fulfill this work. Ten eyes were used to study the gross anatomy of pecten oculi, including the location, shape, and numbers of pleats. Five samples were embedded at 10% neutral buffered formalin. The specimens were examined by regular histological procedures. The latter five samples were applied for electron microscopy.Results:Grossly, the pecten oculi is formed of three portions: the base, emerged from the optic disk; the pleats, sorted in fan shape; and the bridge. The essential histological ingredients of Baladi ducks’ pecten oculi are the blood vessels, lymph vessels, pigment cells, and hyalocytes.Conclusion:The current work explains the primary macro- and micro-morphological features of pecten oculi in Baladi duck and collates these features to those formerly explained in other birds. Generally, pecten oculi of Baladi duck was analogous to that of the diurnal birds.

Comparative morphological and histological study of the pecten oculi in two species of Iraqi birds (Falco tinnunculus L. and Streptopelia decaocto F.)

Study showed structure of pecten oculi in the Kestrel Falco tinnunculus L.wasPleated type and consisted of 17 folds which were thick. While in the Collared DoveStreptopelia decaocto F. was Vaned type and consisted of 13 folds and it describedthin. The illustrated histological study of pecten oculi folds in the Kestrel and theCollared Dove was composed of large number of capillaries, large blood vessels andpigment cells which were few in Kestrel compare with the Collared Dove. The bridgein the Kestrel and the Collared Dove pecten oculi was consisted of connective tissue,many pigment cells, and contains on little capillaries and it linked the membrane tothe internal limiting membrane of the retina in the Kestrel.Key words: birds, pecten oculi, morphology, histology

Comparative morphological and histological study of the pecten oculi in two species of Iraqi birds (Falco tinnunculus L. and Streptopelia decaocto F.)

Study showed structure of pecten oculi in the Kestrel Falco tinnunculus L.wasPleated type and consisted of 17 folds which were thick. While in the Collared DoveStreptopelia decaocto F. was Vaned type and consisted of 13 folds and it describedthin. The illustrated histological study of pecten oculi folds in the Kestrel and theCollared Dove was composed of large number of capillaries, large blood vessels andpigment cells which were few in Kestrel compare with the Collared Dove. The bridgein the Kestrel and the Collared Dove pecten oculi was consisted of connective tissue,many pigment cells, and contains on little capillaries and it linked the membrane tothe internal limiting membrane of the retina in the Kestrel.Key words: birds, pecten oculi, morphology, histology

Ocular Ultrasonography and Biometry in the Cinereous Vulture (Aegypius monachus).

To establish reference standards for ocular ultrasound and biometry, 24 cinereous vultures (Aegypius monachus) (45 eyes) underwent B-mode and A-mode ultrasonographic examination using a 12.5-MHz probe. The vultures were manually restrained without sedation, and the eyes were topically anesthetized. Biometry was performed in the sagittal plane for axial length of the globe (AGL), anterior chamber depth (ACD), lens thickness (LT), and vitreous chamber depth (VCD). Biometry of the pecten oculi (LP) was measured on images of transversal scan at 9 hours. Biometric findings were as follows: AGL=27.74 ± 0.77 mm, ACD=3.73 ± 0.62 mm, LT=5.41 ± 0.18 mm, VCD=18.60 ± 0.58 mm, and LP=10.21 ± 1.19 mm. No correlation was found between body weight and AGL. Right and left globe sizes were not significantly different, but AGL and VCD were significantly longer (P < .05) in male than in female vultures. Including diagnostic protocols such as ocular ultrasound may improve the ophthalmologic care of endangered raptors injured by blunt trauma, when opacities of the ocular media prevent examination of the internal ocular structures.

The use of sulfur hexafluoride microbubbles for contrast-enhanced ocular ultrasonography of the pecten oculi in birds.

The pecten oculi is a vascular and pigmented structure localized within the posterior segment of all avian eyes. Its primary function is not fully understood yet. As ultrasonography (US) is a useful imaging modality for evaluation of the pecten oculi, the objective of this study was to investigate the utility of an intravenous contrast solution of sulfur hexafluoride (SF6) microbubbles as a means of enhancing visualization of the pecten oculi in normal birds. Ten adult individuals of the following avian species were evaluated: 1 roadside hawk (Rupornis magnirostris), 1 stygian owl (Asio stygius), 2 striped owls (Asio clamator), 2 burrowing owls (Athene cunicularia), 2 ring-necked parakeet (Psittacula krameri), and 2 domestic chickens (Gallus gallus domesticus). After baseline ocular sonograms were obtained in sedated animals, 4.5μg/kg of a contrast solution containing SF6 microbubbles was administered intravenously and US of the right eye was immediately performed. US was continued during injection to provide real-time imaging of the pecten oculi during vascular perfusion of contrast material. Within 2-3seconds following intravenous contrast administration, microbubbles reached the pecten oculi of all birds investigated and provided significant ultrasonographic contrast enhancement. SF6 microbubble contrast ultrasonography in birds is a safe and easy procedure that provides increased contrast and enhanced visualization of the pecten oculi. Future use may enable further discovery of its physiologic functions and aid in the development of therapeutic plans for avian intraocular disease.