Ultrastructural study of retinal development in the turtle Trachemys scripta elegans

Segovia, Yolanda; Garcı́a, Magdalena; Gómez‐Torres, María José; Mengual, R.

doi:10.1007/s00435-016-0308-9

Cited by 9 publications

(3 citation statements)

References 40 publications

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“…The orientation of each zone was made following pecten position. The retinas were fixed and processed for optical microscopy analysis as previously described (Segovia et al, 2016). Retina fixation was performed in 1% paraformaldehyde, 1.6% glutaraldehyde in a 0.1 M phosphate buffer (pH 7.4).…”

Section: Methodsmentioning

confidence: 99%

The Structure of the Retina of the Eurasian Eagle-Owl and its Relation to Lifestyle

Alix

Segovia

Garcı́a

2017

Avian Biology Research

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The retinal layers of birds are the same as those of other vertebrates; however, some variations exist in morphology, areas of visual acuity, and retinal vascularisation. Moreover, as a result of the relationship between environment, visual perception and behaviour, some variations are observed between diurnal and nocturnal birds. In this study, we have investigated the retina of the Eurasian Eagle-owl ( Bubo bubo hispanicus) by optical microscopy. The results indicate that the retina has features of both nocturnal and diurnal birds. The pigment epithelium cells have long prolongations filled with melanin granules. The rod is the dominant photoreceptor, but simple cones are abundant. Yellow and colourless oil droplets and paraboloid are present in the inner segment of cones. In the inner nuclear layer, the cell bodies of horizontal cells can easily be recognised by a large and pale cytoplasm. Bipolar cell perikarya are identified by their dark nuclei and the round and narrow cytoplasm. Amacrine cells, located in the inner border of the inner nuclear layer, have a round perikarya and lightly stained nuclei. Müller cells bodies, also located in this region, have an irregular shape. Finally, ganglion cells which are characterised by the prominent nuclei and nucleoli vary in size and abundance depending on different regions in the retina. The morphological characteristics of this retina indicate that B. b. hispanicus have a high light sensitivity, the capacity to discriminate colour, a complex visual processing in the inner retina in order to mediate contrast and motion and, possibly, an elevated acuity in areas of high photoreceptor and ganglion cell density.

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Section: Methodsmentioning

confidence: 99%

The Structure of the Retina of the Eurasian Eagle-Owl and its Relation to Lifestyle

Alix

Segovia

Garcı́a

2017

Avian Biology Research

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“…In accordance with Segovia et al (2016), the retinas were immersed in the fixative (1% paraformaldehyde, 1.6% glutaraldehyde, 0.15 mm CaCl2 in 0.1 M phosphate buffer, pH 7.4) for 2 h at room temperature and then at 4°C overnight. Each retina was divided into central and peripheral zones, and retinal fragments were post‐fixed in 2% OsO4 in an 0.1 M phosphate buffer for 1 h, pH 7.4 and then dehydrated in ascending series of ethanol, cleared in propylene oxide and flat‐embedded in Epon 812 epoxy resin.…”

Section: Methodsmentioning

confidence: 99%

Cone distribution and visual resolution of the yellow‐legged gull, Larus michahellis (Naumann, 1840)

Victory

Segovia

Garcı́a

2021

Anat Histol Embryol

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The morphological characteristics of the yellow‐legged gull's photoreceptors and cone distribution were studied using light and electron microscopy. In wholemount fresh retinas, five different coloured oil droplets located in the cone inner segments could be seen and characterized by colour, diameter and stratification. The photoreceptors were classified by comparing the fresh and fixed vertical sections under a light and electron microscope. Rods were easily distinguished from cones based on the outer segment morphology and the absence of oil droplets in their inner segments. Four types of single cones were associated with red, yellow, colourless and transparent oil droplets. Unequal double cones comprised a long principal member with a green oil droplet and an accessory short member containing a green microdroplet which was highly electron‐dense under electron microscopy. The different types of oil droplets were counted from microphotographs of fresh retinal samples in 20 regions. The density, percentage and diameter of the oil droplets were determined. The results showed that central regions had the highest oil droplet density which decreased towards the retinal periphery in all quadrants. Moreover, the oil droplet density was higher in the dorsotemporal quadrant than in other retinal regions. The average density of the red oil droplets was highest in the central areas, whereas colourless oil droplets had the highest density throughout the retina. In contrast, transparent oil droplets had the lowest density across all the regions of the retina. Finally, the retinal resolution was 52.61 cycles/degree. It was calculated using the posterior nodal distance and the oil droplet diameter. The work concludes by discussing the significance of the relative proportion of different cone types across the retina.

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“…There are some previously published data describing the gross morphological appearance especially the retina of different avian species (Alix, Segovia, & García, 2017; Bawa & YashRoy, 1972; Braekevelt & Thorlakson, 1993; El‐Beltagy, 2015; Hossler & Olson, 1984; Segovia, García, Gómez‐Torres, & Mengual, 2016). However, the cornea, iris, and choroid received little attention from researchers (Meyer, 1977).…”

Section: Introductionmentioning

confidence: 99%

Visual adaptation and retinal characterization of the Garganey (Anas querquedula): Histological and scanning electron microscope observations

Bassuoni

Abumandour

El‐Mansi

et al. 2021

Microscopy Res & Technique

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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.

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Ultrastructural study of retinal development in the turtle Trachemys scripta elegans

Cited by 9 publications

References 40 publications

The Structure of the Retina of the Eurasian Eagle-Owl and its Relation to Lifestyle

The Structure of the Retina of the Eurasian Eagle-Owl and its Relation to Lifestyle

Cone distribution and visual resolution of the yellow‐legged gull, Larus michahellis (Naumann, 1840)

Visual adaptation and retinal characterization of the Garganey (Anas querquedula): Histological and scanning electron microscope observations

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