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

Abstract

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.

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

“…Additionally, the pecteneal apex differs slightly between different species of birds. In this study, the free pecteneal apex was fused with one another, forming a free apical bridge that was directed towards the gelatinous vitreous body and ciliary body, similar to what was seen in a variety of diurnal birds, such as the migratory Garganey, budgerigar, black kite, chicken, white stork, Baladi ducks, common buzzard, seagulls, northern bald ibis, and migratory European wild quail (Abumandour et al, 2021;Abumandour et al, 2022;Alan et al, 2020;Gültiken et al, 2012;Ince et al, 2017;Kiama et al, 1994;Micali et al, 2012;Moselhy & El-Hady, 2019;Onuk, Tutuncu, et al, 2013;Puzzolo et al, 1985;Yilmaz et al, 2021), while the free pecteneal apex…”

“…These coiled surfaces provide a large surface area for efficient nutrient exchange between the blood capillaries and the retina; additionally, this specialized structure helps to maintain the health and functionality of the non-vascular retina by ensuring a constant supply of nutrients. Moreover, high SEM magnification showed that the pecteneal pleat's outer surface is covered by a thin smooth vitreopecteneal limiting membrane separating the pleat's outer surface from the gelatinous vitreous body, similar to that observed in many avian species (Abumandour et al, 2021;Abumandour et al, 2022;Elghoul et al, 2022;Kandyle et al, 2022;Uehara et al, 1996).…”

“…SEM and histological studies of the two examined carnivorous birds revealed that the highly vascularized intra‐ocular pecten oculi with their highly black pigmentations in the nocturnal little owl and the slightly black or brown pigmentations in the diurnal common kestrel were derived from the inner retinal surface, which is situated above the optic nerve, and attached with the gelatinous vitreous body in an oblique direction towards the ciliary body, similar to that described in all avian species with different feeding habits and unique visual activity clock hours (Abumandour et al, 2022; Braekevelt & Richardson, 1996; Elghoul et al, 2022; Kandyle et al, 2022; Kiama et al, 2001; Orhan et al, 2011; Yilmaz et al, 2021).…”

“…Generally, based on the previously published data, there is a variation in the pecten oculi configurations in the different birds, including cone, vane, fold, and plicate. The plicated (folded) pecten oculi was described in this study and the Glossy Ibis (Kandyle et al, 2022); the folded pecten was seen in the Eurasian moorhen (Abumandour et al, 2021); the plicated pecten was seen in some avian species such as the migratory Garganey and European wild quail (Abumandour et al, 2021;Abumandour et al, 2022); the vane-pecten was seen in the common ostrich (Elghoul et al, 2022;Kiama et al, 2006); and the cone-pecten was seen in the Kiwis (Baumel et al, 1993).…”

“…However, in the European wild quail (Abumandour et al, 2022) observed that the phosphate is the lowest element percent at the apical part and the sulfate is the lowest element percent at the middle and base pecteneal parts. The SEM/EDX elemental analysis confirmed the presence of oxygen, carbon, nitrogen, and aluminum in varying percentages within the pecten oculi; these findings contribute to our understanding of this unique avian organ's structural and functional characteristics.…”