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.

The effects of intravitreally injected bevacizumab on the retina and retina pigment epithelium: experimental in-vivo electron microscopic study in intact versus vitrectomized eyes

Open Medicine ◽  
2010 ◽  
Vol 5 (6) ◽  
pp. 745-751 ◽  
Author(s):  
Nilufer Kocak ◽  
Candan Ozogul ◽  
Suleyman Kaynak ◽  
Ulker Sonmez ◽  
Mehmet Zengin ◽  
...  
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Intravitreal Bevacizumab ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Control Group ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Electron Microscopes

AbstractTo analyze the retinal toxicity of bevacizumab at various doses both in vitrectomized and non-vitrectomized rabbit models. Twenty- eight rabbits were included in the study. Twenty- four rabbits were assigned to six groups, with 4 of the rabbits in the control group. The animals in Groups 1, 2 and 3 received bevacizumab at a dose of 0.3 mg, 0.5 mg and 1.5 mg /eye, respectively. The rabbits in Groups 4, 5 and 6 received intravitreal bevacizumab of 0.3 mg, 0.5 mg and 1.5mg/eye, respectively, after gas compression vitrectomy. Two weeks after the procedure, the rabbits were euthanized. Retina tissue samples were then obtained and examined with both light and electron microscopes. In Groups 1, 2 and 3 after bevacizumab injection, toxic degeneration in the photoreceptor and retinal pigment epithelium cells was observed via electron microscopic examination. The findings in Groups 4 and 5 were normal as compared to the control group. In Group 6, toxicity in the bipolar neurons and photoreceptor cells was noticed. Increased toxicity and retinal penetration were noticed in all administered doses of bevacizumab in the presence of vitreous. In addition, ocular toxicity occurred through the injection of the highest dose of bevacizumab after vitrectomy. It is possible that the bevacizumab dose and the, vitreous are as important as the drug half-life in the vitreous.

scholarly journals UNC569-induced Morphological Changes in Pigment Epithelia and Photoreceptor Cells in the Retina through MerTK Inhibition in Mice

2018 ◽  
Vol 46 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Ayako Sayama ◽  
Keiko Okado ◽  
Koichi Nakamura ◽  
Tatsuya Kawaguchi ◽  
Takuma Iguchi ◽  
...  
Keyword(s):  
Tissue Sample ◽  
Morphological Changes ◽  
Pigment Epithelium ◽  
Outer Nuclear Layer ◽  
Retinal Pigment ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Electron Microscopic ◽  
Drug Induced ◽  
Photoreceptor Outer Segments

Mer proto-oncogene tyrosine kinase (MerTK), which is expressed in the retinal pigment epithelium (RPE), regulates phagocytosis of shed photoreceptor outer segments (POS). To investigate the effects of drug-induced MerTK inhibition on the retina, UNC569, a specific MerTK inhibitor, was orally administered to male mice at a concentration of 60, 100, or 150 mg/kg for up to 14 days. Furthermore, MerTK inhibition in the retinal tissue sample was examined using a phosphorylation assay following a single dose of UNC569 at 100 mg/kg. In electron microscopic examination, UNC569 at 100 mg/kg or more increased phagosomes and phagolysosomes in the RPE. In addition, UNC569 at 150 mg/kg increased chromatin-condensed nuclei in the outer nuclear layer, indicating the early phase of apoptosis of photoreceptor cells. MiR-183, miR-96, and miR-124, which are enriched in photoreceptor cells, were elevated in the plasma of mice following treatment of 150-mg/kg UNC569, in conjunction with the photoreceptor lesion. Additionally, 100-mg/kg UNC569 inhibited MerTK phosphorylation in the retina. These results suggest that MerTK inhibition impaired phagocytic function of the retina, leading to accumulation of shed POS within the POS layer and increasing phagosomes and phagolysosomes in the RPE to delay POS renewal, resulting in apoptosis of photoreceptor cells.

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 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.

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.

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.

A Bibliometric Analysis of the Top 100 Cited Papers in Retinal Detachment

2021 ◽  
pp. 247412642110073
Author(s):  
Masumi George Asahi ◽  
Haig Pakhchanian ◽  
Christine Doepker ◽  
Rahul Raiker ◽  
Ron P. Gallemore
Keyword(s):  
Retinal Detachment ◽  
Bibliometric Analysis ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Microscopic Analysis ◽  
The United States ◽  
Electron Microscopic ◽  
Research Areas ◽  
Science Index ◽  
Funding Agencies

Purpose: This work aimed to identify and analyze the most frequently cited articles in retinal detachment (RD). Methods: Institute for Scientific Information’s Web of Science index (Thomas Scientific) was used to identify the top 100 most cited articles on RD between 1900 and 2019. Data from the top 100 most cited articles that met inclusion criteria were analyzed based on title, citation frequency, authorship, institution, journal, year of publication, and country of origin. Results: The top 100 articles in RD were cited 88 to 480 times. Steven K. Fisher was the most cited individual, with the University of California system being the most cited organization. Sixty-four percent of the top 100 articles originated from the United States and were published in the American Journal of Ophthalmology, Ophthalmology, and Archives of Ophthalmology at frequencies of 36%, 24%, and 11%, respectively. The top funding agencies included the US Department of Health and Human Services, the National Institutes of Health, and the National Eye Institute at 29%, 28%, and 27%, respectively. The top-cited article, which assessed the role of the retinal pigment epithelium by histologic and electron microscopic analysis of RDs in eyes of owl monkeys, was by Machemer and Laqua in the American Journal of Ophthalmology. Conclusions: This bibliometric analysis provides researchers and clinicians with a detailed overview of the most cited manuscripts in RD. Such analyses may guide researchers and funding agencies on important research areas in the field.

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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