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.

Ultrastructural Changes of Smoooth Endoplasmic Reticulum in the Retinal Pigment Epithelium by Choline Chloride

1972 ◽  
Vol 30 ◽  
pp. 58-59
Author(s):  
Kazushige Hirosawa ◽  
Eichi Yamada
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cell ◽  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Choline Chloride ◽  
Retinal Pigment ◽  
Ultrastructural Changes ◽  
Lower Vertebrate ◽  
Visual Cells ◽  
Pigment Epithelial

The pigment epithelium is located between the choriocapillary and the visual cells. The pigment epithelial cell is characterized by a large amount of the smooth endoplasmic reticulum (SER) in its cytoplasm. In addition, the pigment epithelial cell of some lower vertebrate has myeloid body as a specialized form of the SER. Generally, SER is supposed to work in the lipid metabolism. However, the functions of abundant SER and myeloid body in the pigment epithelial cell are still in question. This paper reports an attempt, to depict the functions of these organelles in the frog retina by administering one of phospholipid precursors.

scholarly journals Ultrastructural changes in the vessels and capillaries of the choroid and in the retina of rats caused by a mixture of alcohols (40% ethanol and 100% methanol)

2019 ◽  
Vol 79 (3) ◽  
pp. 58-63
Author(s):  
N. Molchaniuk
Keyword(s):  
Toxic Effect ◽  
Ganglion Cells ◽  
Smooth Endoplasmic Reticulum ◽  
Pigment Epithelium ◽  
Photoreceptor Cells ◽  
Ultrastructural Changes ◽  
Retinal Area ◽  
Pathological Changes ◽  
Rpe Cells ◽  
Pure Methanol

We was study the ultrastructure of blood vessels and capillaries of the choroid (CO), retina's pigment epithelium (RPE), it's photoreceptor cells, ganglion cells, shoots of Muller cells of rats, that surround them, after in traperit one alinjection of a mixture of alcohols (40% ethanol and 100% methanol) in a 3:1 ratio and separately pure methanol (the methanol dose in each group was 0.75 g/kg rat body weight) in a PEM-100-01 electron microscope (Ukraine) in the period from 1 h10 min to 14 days after the alcohols injection. It was shown that the most sensitive structures to the toxic effect of a mixture of alcohol swere endothelial cells of CO and RPE cells. Pathological changes in RPE cells consistin alteration of mitochondria, in destructi on of the elements of the smooth endoplasmic reticulum and other organelles, in alignment of folds on the basal side of the cell sand in the destruction of apical microvilli. Significant destructive changes in its cells were not as early as 1 h10 min after ijection. In the dynamics of the study 1 h 10 min to 14 days the phenomenon of hydropic dystrophy and elements of destruction of organelles in the studied cells gradually progressed with simultaneous enhancement in the cells of the compensatory-restorative processes. After the injection of pure methanol, pathological changes in the chronic retinal area and in the retina are unidirectional except for the first 3 hours. Ethanol potentiates the toxic effect of methanol in the initial observation terms and leads to deeper damage to the rat CO and RPE ultrastructure. The leading place in the amplification of pathological changes in the investigated structures, after injection of the alcohols' mixture, is given to methanol.

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.

scholarly journals The Impact of the Timing of Dosing on the Severity of UNC569-Induced Ultrastructural Changes in the Mouse Retina

2020 ◽  
Vol 48 (5) ◽  
pp. 669-676
Author(s):  
Ayako Sayama ◽  
Keiko Okado ◽  
Mayu Yamaguchi ◽  
Naozumi Samata ◽  
Masako Imaoka ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Ultrastructural Changes ◽  
Mouse Retina ◽  
Visual Cycle ◽  
Electron Microscopic ◽  
The Impact

Mer proto-oncogene tyrosine kinase (MerTK), expressed in the retinal pigment epithelium (RPE), regulates the phagocytosis of shed photoreceptor outer segments. To investigate the influence of dosing time on MerTK inhibitor UNC569-induced retinal toxicity, UNC569 at 100 mg/kg was orally administered to male mice at 2 different Zeitgeber times (ZT5.5 or ZT22) for 28 days. Electron microscopy was conducted at ZT2 after the final dosing. Additionally, the visual cycle components (11-cis-retinal, all-trans-retinal, all-trans-retinol, and 11-cis-retinol), which play an important role in maintaining retinal homeostasis, were quantified by liquid chromatography/mass spectrometry/mass spectrometry. Under electron microscopic examination, the number of phagosomes and phagolysosomes in the RPE increased in both the ZT5.5 and ZT22 administered groups, while endoplasmic reticulum dilatation in the RPE and chromatin aggregation of photoreceptor nuclei were observed only in the ZT22 administered group. No change was observed in any of the visual cycle components. These results suggest that the timing of the dosing in relation to the physiological MerTK phosphorylation affected the severity of changes in the RPE, leading to the apoptosis of the photoreceptor cells.

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.

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.

scholarly journals Phagocytosis of Retinal Rod and Cone Photoreceptors

Physiology ◽  
2010 ◽  
Vol 25 (1) ◽  
pp. 8-15 ◽  
Author(s):  
Brian M. Kevany ◽  
Krzysztof Palczewski
Keyword(s):  
Outer Segment ◽  
Photoreceptor Cell ◽  
Current Knowledge ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Cells ◽  
Constant Length ◽  
Outer Segments ◽  
Retinal Rod ◽  
Rod And Cone Photoreceptors

Photoreceptor cells maintain a roughly constant length by continuously generating new outer segments from their base while simultaneously releasing mature outer segments engulfed by the retinal pigment epithelium (RPE). Thus postmitotic RPE cells phagocytose an immense amount of material over a lifetime, disposing of photoreceptor cell waste while retaining useful content. This review focuses on current knowledge of outer segment phagocytosis, discussing the steps involved along with their critical participants as well as how various perturbations in outer segment (OS) disposal can lead to retinopathies.

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