Fine structure of the retinal pigment epithelium and photoreceptor cells of an Australian marsupial Setonix brachyurus

1973 ◽  
Vol 51 (10) ◽  
pp. 1093-1100 ◽  
Author(s):  
C. R. Braekevelt
Keyword(s):  
Retinal Pigment Epithelium ◽  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Single Layer ◽  
Photoreceptor Cells ◽  
Rods And Cones ◽  
Outer Border ◽  
Large Lipid Droplet ◽  
Australian Marsupial

The morphology of the retinal pigment epithelium and photoreceptor cells has been studied in the quokka (Setonix brachyurus), an Australian marsupial, by light and electron microscopy.The pigment epithelium is formed by a single layer of cuboidal cells which are separated from the choriocapillaris by multilayered Bruch's membrane. Each epithelial cell is rich in organelles and inclusions, including smooth endoplasmic reticulum, mitochondria, Golgi complexes, phagosomes, and pigment granules. The outer border of the epithelial cells is highly infolded while the inner surface displays numerous processes which surround both rod and cone photoreceptor outer segments.Three photoreceptor types are seen, single rods, single cones, and twin cones. The rod photoreceptors outnumber the cones about 50 to 1 and are smaller and more electron-dense than the cones. The cones possess a large lipid droplet within their inner segments. Twin cones are seen only occasionally. They are formed by two cones lying in close apposition, with each member being morphologically quite similar to the other and to the single cone.Photoreceptor synapses in both rods and cones appear to be formed by superficial and invaginated contacts with bipolar and horizontal cells.

JAM-C maintains VEGR2 expression to promote retinal pigment epithelium cell survival under oxidative stress

2017 ◽  
Vol 117 (04) ◽  
pp. 750-757
Author(s):  
Xin Jia ◽  
Chen Zhao ◽  
Qishan Chen ◽  
Yuxiang Du ◽  
Lijuan Huang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinal Pigment Epithelium ◽  
Cell Survival ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Retinal Pigment Epithelium Cell ◽  
Photoreceptor Cells ◽  
Rpe Cells

SummaryJunctional adhesion molecule-C (JAM-C) has been shown to play critical roles during development and in immune responses. However, its role in adult eyes under oxidative stress remains poorly understood. Here, we report that JAM-C is abundantly expressed in adult mouse retinae and choroids in vivo and in cultured retinal pigment epithelium (RPE) and photoreceptor cells in vitro. Importantly, both JAM-C expression and its membrane localisation are downregulated by H2O2-induced oxidative stress. Under H2O2-induced oxidative stress, JAM-C is critically required for the survival of human RPE cells. Indeed, loss of JAM-C by siRNA knockdown decreased RPE cell survival. Mechanistically, we show that JAM-C is required to maintain VEGFR2 expression in RPE cells, and VEGFR2 plays an important role in keeping the RPE cells viable since overexpression of VEGFR2 partially restored impaired RPE survival caused by JAM-C knockdown and increased RPE survival. We further show that JAM-C regulates VEGFR2 expression and, in turn, modulates p38 phosphorylation. Together, our data demonstrate that JAM-C plays an important role in maintaining VEGR2 expression to promote RPE cell survival under oxidative stress. Given the vital importance of RPE in the eye, approaches that can modulate JAM-C expression may have therapeutic values in treating diseases with impaired RPE survival.

Studies on the eyes of catfishes with special reference to the tapetum lucidum

1974 ◽  
Vol 186 (1082) ◽  
pp. 13-36 ◽  
Keyword(s):  
Ictalurus Punctatus ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Single Layer ◽  
High Refractive Index ◽  
Extensive Study ◽  
Rods And Cones ◽  
Light Yellow ◽  
Membrane Bound ◽  
Pigment Epithelial Cells

Marine catfishes (Ariidae) and freshwater catfishes (Ictaluridae) have ocular tapeta lucida. Species examined were Bagre marinus (Mitchill), Arius felis (L.), Ictalurus punctatus (Rafinesque), I. natalis (Lesueur), I. nebulosus (Lesueur) and Pylodictis olivaris (Rafinesque). The tapeta are white reflectors located in the pigment epithelium; they occupy most of the fundus except for a narrow black ventral field. A more extensive study was made of the tapetum of the hardhead catfish A. felis . In histologic sections the tapetum is yellow brown and is easily confused with retinal pigment. It can be distinguished because it stains with ferric-ferricyanide and dissolves in methanol-hydrochloric acid after Carnoy fixation. The tapetum is occluded by melanosomes which move inwards in light, and it is exposed by movement outwards of melanosomes in dim light or darkness. Electron microscopy shows that processes of the pigment epithelial cells contain many membrane-bound tapetal spheres which enclose the tapetal pigment and are responsible for reflexion of light. Spheres are 370 nm in diameter (average); there are about 5.5 spheres in 1 μm 3 , and the tapetum is about 90 μm thick. Rods and cones are equal in number; rods form a single layer, cones are single and possess an accessory outer segment. Transmission of the tapetum is minimal at short wavelengths and rises steadily above 500 nm. Reflectance is diffuse; it rises to a maximum at 500 nm, and is high at long wavelengths. The tapetum has a high refractive index, ca . 1.56, favouring light scattering. Some characteristics of the extracted tapetal pigment are pre­sented: it is light yellow, and absorbance maxima occur at 260 and 330 nm in acidic meth­anol. The pigment epithelium contains lysosome-like bodies but no myeloid bodies. The hardhead retina contains a visual pigment 527 2 . Measurements of natural light (irradiance) in coastal waters inhabited by sea catfishes are presented: the waters are turbid and transmit maximally at 575 to 580 nm. The findings, in relation to earlier work on the catfish eye, performance of the eye and habits of the fish are discussed.

Pathways for the uptake and conservation of docosahexaenoic acid in photoreceptors and synapses: biochemical and autoradiographic studies

1993 ◽  
Vol 71 (9) ◽  
pp. 690-698 ◽  
Author(s):  
Nicolas G. Bazan ◽  
Elena B. Rodriguez de Turco ◽  
William C. Gordon
Keyword(s):  
Fatty Acid ◽  
Retinal Pigment Epithelium ◽  
Docosahexaenoic Acid ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Plasma Lipoproteins ◽  
Rod Photoreceptor ◽  
Excitable Membranes ◽  
The Central Nervous System

Docosahexaenoic acid (22:6n−3) esterified into phospholipids represents by far the most prevalent fatty acid of rod photoreceptor disc membranes and synaptic terminals. During synaptogenesis and photoreceptor biogenesis, plasma lipoproteins, secreted mainly by the liver, are the main source of plasma 22:6n−3 for the central nervous system. This systemic route (the long loop) also operates in mature animals for morphogenesis and maintenance of excitable membranes (e.g., during constant renewal of photoreceptor disc membranes). When radiolabeled 18:3n−3, the dietary precursor of 22:6n−3, is systemically supplied to 3-day-old mouse pups, it is elongated and desaturated in the liver, leading to the synthesis of 22:6n−3 – lipoproteins that shuttle the fatty acid through the bloodstream to retina and brain. When radiolabeled 22:6n−3 was used, a more efficient labeling of brain and retinal lipids was achieved. The retinal pigment epithelium is involved, not only in the uptake of 22:6n−3 from circulating lipoproteins in the choriocapillaris but also in the recycling of 22:6n−3 from degraded phagosomal phospholipids back to the inner segments of photoreceptors (the short loop), following each phagocytic event. An interplay among efficient 22:6n−6 delivery from the liver, selective uptake by retinal pigment epithelium photoreceptor cells, and avid retinal retention may contribute to the enrichment of excitable membranes of the retina with 22:6n−3 – phospholipids.Key words: docosahexaenoic acid, phospholipids, photoreceptors.

scholarly journals THE RENEWAL OF PHOTORECEPTOR CELL OUTER SEGMENTS

1967 ◽  
Vol 33 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Richard W. Young
Keyword(s):  
Amino Acid ◽  
Retinal Pigment Epithelium ◽  
Ambient Temperature ◽  
Outer Segment ◽  
Photoreceptor Cell ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Radioactive Material ◽  
Retinal Photoreceptor

The utilization of methionine-3H by retinal photoreceptor cells has been studied by radioautographic technique in the rat, mouse, and frog. In all three species, the labeled amino acid is concentrated initially in the inner segment of the cell. Within 24 hr, the radioactive material is displaced to the base of the outer segment, where it accumulates as a distinct reaction band. The reaction band then gradually moves along the outer segment and ultimately disappears at the apex of the cell, which is in contact with the retinal pigment epithelium. These findings are interpreted to indicate that the photoreceptor cell outer segment is continually renewed, by the repeated lamellar apposition of material (membranous discs) at the base of the outer segment, in conjunction with a balanced removal of material at its apex. The outer segment renewal rate is accelerated in frogs when ambient temperature is raised, and is elevated in both frogs and rats when the intensity of retinal illumination is increased.

Transplantation of Human Fetal Retinal Pigment Epithelium Rescues Photoreceptor Cells from in the Royal College of Surgeons Rat Retina.

Retina ◽  
1997 ◽  
Vol 17 (5) ◽  
pp. 469-470
Author(s):  
C. W. Little ◽  
B. Castillo ◽  
D. A. DiLoreto ◽  
C. Cox ◽  
J. Wyatt ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Royal College ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Rat Retina

scholarly journals Effect of methanol on the ultrastructure of chorioretinal complex of rats’ eyes in the early stages of the experiment

2014 ◽  
Vol 18 (1 (69)) ◽  
Author(s):  
N. І. Molchanyuk
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Electron Microscopic ◽  
White Rats ◽  
Intraperitoneal Dose ◽  
A Cell ◽  
Number Of Cells ◽  
Observation Period

Electron-microscopic structure of the chorioretinal complex were investigated (СRC), [choriocapillaries (HC) – retinal pigment epithelium (RPE) – photoreceptor cells (FC)], of white rats in a period of 40 min. to 3 days after a single intraperitoneal dose of methanol 0.75 g/kg body weight. It has been established that RPE cells are the most responsiveto the dose of the methanol used. In the dynamics (from 40 min. up to 3 days), they grew destructive changes of mitochondria and elements of smooth endoplasmic reticulum, the smoothness of the basal folds and patchy destruction of the apical microvilli. The changes in CC and FC were similar. By the end of the observation period, these phenomena in the CRC structure spread to a larger number of cells. At the same time, during the whole period of the study, and, in particular, after a day, some signs of recovery of compensatory nature were obvious. Attention is drawn to pronounced reaction of mitochondria, which are energy forming structures of a cell.

scholarly journals Dynamics of ultrastructural changes in the chorioretinal complex of rat eyes induced by high dose of methanol

2016 ◽  
Vol 71 (1) ◽  
pp. 36-40
Author(s):  
N. Molchanyuk
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Ultrastructural Changes ◽  
High Dose ◽  
Regenerative Processes ◽  
Retinal Photoreceptor ◽  
Local Destruction ◽  
Destructive Processes

The structure of chorioretinal complex (CRC) of rat eyes was studied by electron microscopy: choriocapillaris, retinal pigment epithelium (RPE) and retinal photoreceptor cells after 40 minutes, 1 hour and 10 minutes, on the first 1 st , 3 rd , 7 th and 14 th days after a single intraperitoneal injection of methanol in a dose of 7.0 g/kg of body weight. It was shown that the primary and significant destructive changes in the structures of the studied complex were observed in the RPE cells, which are characterized by alteration of mitochondria and tubules of smooth endoplasmic reticulum, equation of basal folds and local destruction of the apical microvilli. The destructive processes in the cells were growing in the dynamics of CRC structures research. In parallel, the features of compensatory-regenerative processes in these cells were detected.

Transplantation of Human Fetal Retinal Pigment Epithelium Rescues Photoreceptor Cells from in the Royal College of Surgeons Rat Retina

Retina ◽  
1997 ◽  
Vol 17 (5) ◽  
pp. 469
Author(s):  
C. W. Little ◽  
B. Castillo ◽  
D. A. DiLoreto ◽  
C. Cox ◽  
J. Wyatt ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Royal College ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Rat Retina
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