Browsing by Subject "Retinal pigment epithelium"

Now showing 1 - 6 of 6
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    Fine structure of the retinal pigment epithelium of the mallard duck (Anas platyrhynchos)
    (Murcia : F. Hernández, 1990) Braekevelt, Charlie R.
    As part of a comparative morphological study, the fine structure of the retinal pigment epithelium (RPE), the choriocapillaris and Bruch's membrane (complexus basalis) has been investigated by light and electron microscopy in the mallard (Anas platyrhynchos). In this species the RPE consists of a single layer of cuboidal cells which display numerous very deep basa1 (scleral) infoldings and extensive apical (vitreal) processes which enclose photoreceptor outer segments. The RPE cells are joined laterally by prominent basally-located tight junctions. Internally smooth endoplasmic reticulum is the most abundant cell organelle with only small amounts of rough endoplasmic reticulum present. Polysomes are abundant as are basally-located mitochondria which often displayed a ring-shaped profile. The cell nucleus is large and vesicular. Melanosomes are plentiful only within the apical processes of the RPE cells in the light-adapted state. Myeloid bodies are large and numerous and very often have ribosomes on their outer surface. Bruch's membrane (complexus basalis) shows a pentalaminate structure but with only a poorly represented central elastic lamina. Profiles of the choriocapillaris are relatively small and the endothelium of these capillaries while extremely thin facing the retinal epithelium is but minimally fenestrated.
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    Human retinal pigment epithelial SPARC expression and age: an immunohistochemical study
    (Murcia : F. Hernández, 2010) Howard, Claire; Garcia Fiñana, Marta; Yan, Qi; Hiscott, Paul
    The aim of this study was to investigate the temporal and spatial expression of the matricellular protein SPARC (Secreted Protein, Acidic and Rich in Cysteine; also known as osteonectin) in human retinal pigment epithelial (RPE) cells, and compare the results with Bruch’s membrane thickness, employing immunohistochemistry. Eyes from 36 human donors, 16 being ≤65 and 20 >65 years old, were included in the study. Intensity of SPARC immunoreactivity was evaluated using Aequitas Image Analysis software with two-way analysis of variance (ANOVA). Bruch’s membrane thickness was assessed by profile analysis and the association between RPE SPARC immunoreactivity and Bruch’s membrane thickness was investigated by fitting a linear mixed effects model to the data set. Intensity of SPARC immunostaining in RPE cells was significantly lower in older donors (p<0.05 and p<0.001 for posterior and peripheral RPE cells, respectively). The anatomical localisation of the RPE cells also affected the intensity of SPARC staining, which was lower in posterior compared to peripheral cells (p<0.01). No correlation was observed between SPARC immunoreactivity in RPE cells and the thickness of the underlying Bruch’s membrane, in either posterior or peripheral regions. Our results suggest that RPE cell SPARC levels decline with age, a change that may play a role in the pathogenesis of age-related diseases such as age-related macular degeneration.
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    MMP-3 Deficiency Alleviates Endotoxin-Induced Acute Inflammation in the Posterior Eye Segment
    (MDPI, 2016-11-01) Van Hove, Inge; Lefevere, Evy; De Groef, Lies; Sergeys, Jurgen; Libert, Claude; Vandenbroucke, Rossmarijn; Moons, Lieve; Salinas Navarro, Manuel Ángel; Anatomía Humana y Psicobiología
    Matrix metalloproteinase-3 (MMP-3) is known to mediate neuroinflammatory processes by activating microglia, disrupting blood–central nervous system barriers and supporting neutrophil influx into the brain. In addition, the posterior part of the eye, more specifically the retina, the retinal pigment epithelium (RPE) and the blood–retinal barrier, is affected upon neuroinflammation, but a role for MMP-3 during ocular inflammation remains elusive. We investigated whether MMP-3 contributes to acute inflammation in the eye using the endotoxin-induced uveitis (EIU) model. Systemic administration of lipopolysaccharide induced an increase in MMP-3 mRNA and protein expression level in the posterior part of the eye. MMP-3 deficiency or knockdown suppressed retinal leukocyte adhesion and leukocyte infiltration into the vitreous cavity in mice subjected to EIU. Moreover, retinal and RPE mRNA levels of intercellular adhesion molecule 1 (Icam1), interleukin 6 (Il6), cytokine-inducible nitrogen oxide synthase (Nos2) and tumor necrosis factor α (Tnfα), which are key molecules involved in EIU, were clearly reduced in MMP-3 deficient mice. In addition, loss of MMP-3 repressed the upregulation of the chemokines monocyte chemoattractant protein (MCP)-1 and (C-X-C motif) ligand 1 (CXCL1). These findings suggest a contribution of MMP-3 during EIU, and its potential use as a therapeutic drug target in reducing ocular inflammation.
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    Retinal epithelial fine structure in the vervet monkey (Cercopithecus aethiops)
    (Murcia : F. Hernández, 1988) Braekevelt, Charlie R.
    The morphology of the retinal pigment epithelium (RPE) and closely associated Bruch's membrane (complexus basalis) and choriocapillaris have been investigated by electron microscopy in the vervet monkey (Cercopithecus aethiops). The RPE is composed of a single layer of cuboidal cells joined laterally by apically-located junctional complexes. Basally (sclerally) these cells display numerous infoldings while apically (vitreally) abundant processes enclose and interdigitate with rod outer segments. Internally the large vesicular nucleus is centrally located and smooth endoplasmic reticulum. mitochondria and lysosome-like bodies. are plentiful. Rough endoplasmic reticulum, polysomes and melanosomes while present are not abundant. Phagosomes of outer segment discs are noted in various stages of uptake and degradation. The choriocapillaris is highly fenestrated over large areas. Bruch's membrane shows the typical pentalaminate structure noted in other mammalian species without a tapetum lucidum.
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    Retinal pigment epithelial fine structure in the bobtail goanna (Tiliqua rugosa)
    (Murcia : F. Hernández, 1989) Braekevelt, Charlie R.
    The retinal pigment'epithelium (RPE), the choriocapillaris and Bruch's membrane (complexus basalis) have been studied by light and electron microscopy in the bobtail goanna (Tiliqua rugosa) an Australian diurna1 lizard. The RPE consists of a single layer of cuboidal cells which display very deep and tortuous basal (choroidal) infoldings as well as numerous apical (vitreal) processes which interdigitate with the photoreceptor cells. The lateral cell borders are relatively smooth and joined by basally located tight junctions. Internally smooth endoplasmic reticulum is abundant while rough endoplasmic reticulum is not. The RPE cell nucleus is large and vesicular and basally located in the light-adapted state. Polysomes, mitochondria and myeloid bodies are present and widely distributed. Melanosomes are plentiful in the apical region of the epithelial cells in light-adaptation. Bruch's membrane is pentalaminate with the basal lamina of the choriocapillaris being exceptionally thick. The choriocapillaris is a single layer of large-caliber capillaries with thin but only moderately fenestrated endothelium. Numerous dense granules are always present within these endothelial cells.
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    Ultrastructure of the Outer Retina in the Killifish, Aphanius sirhani (Cyprinodontidae, Teleostei)
    (Murcia : Universidad de Murcia, Servicio de Publicaciones, 2010) Mohammad Amin Al-Adhami; Janti Qar; Muneir AlKhdour
    The ultrastructure of the outer retina in the endangered killifish, Aphanius sirhani was studied. The retina shows all eight layers and two membranes typical of vertebrates. The retinal pigment epithelium (RPE) consists of a single layer of closely packed, polygonal, low columnar cells. These cells have large, vesicular nuclei, well developed smooth endoplasmic reticulum, and well developed mitochondria. Phagosomes, lipid droplets and myeloid bodies are also evident. The cells bear numerous apical processes that, in light-adapted fish, interdigitate with the photoreceptor outer segments. The retina is of the duplex type, i.e. contains rods and cones. A variety of cones have been recorded in the present species. These include short, intermediate and long single cones, double and triangular, triple cones. Rod spherules each with a single synaptic ribbon and cone pedicles, each with several synaptic ribbons have been recorded in the outer plexiform layer.