Effect of glycosaminoglycans on rod outer segment phagocytosis by retinal pigment epithelium explants

1988 ◽  
Vol 16 (3) ◽  
pp. 319-320 ◽  
Author(s):  
CHERYL Y. GREGORY ◽  
CAROLYN A. CONVERSE ◽  
WALLACE S. FOULDS
Keyword(s):  
Retinal Pigment Epithelium ◽  
Outer Segment ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Rod Outer Segment

scholarly journals Intracellular topography of rhodopsin regeneration in vertebrate rods.

1985 ◽  
Vol 86 (3) ◽  
pp. 413-422 ◽  
Author(s):  
T P Williams ◽  
J S Penn
Keyword(s):  
Retinal Pigment Epithelium ◽  
Epithelial Cells ◽  
Visual Pigment ◽  
Outer Segment ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Rod Outer Segment

The vertebrate visual pigment of rods, rhodopsin, bleaches in light and regenerates in darkness. When the bleaching and regeneration are carried out in vivo, it is found that the regeneration takes place at nonuniform rates along the rod outer segment (ROS): toads and frogs regenerate rhodopsin faster in the proximal ends of the ROS than in the distal ends. Rats do the reverse. These patterns of regeneration persist whether the bleaching is done with flashes or with steady light. They are also independent of the extent to which the retinal pigment epithelium contains melanin. Furthermore, the dichotomy of patterns (proximal faster vs. distal faster) does not seem to depend upon the presence of an excess of stored retinoid in the eye. Instead, it is suggested that the villous processes of the epithelial cells may play an important role in the regeneration patterns. These processes in amphibia extend nearly to the rod inner segment but in the rat they surround only the apical end of the outer segment. If they "funnel" the retinoids back to the ROS, their location and morphology could explain the two different kinds of patterns seen.

scholarly journals Light-induced Oxidation of Photoreceptor Outer Segment Phospholipids Generates Ligands for CD36-mediated Phagocytosis by Retinal Pigment Epithelium

2006 ◽  
Vol 281 (7) ◽  
pp. 4222-4230 ◽  
Author(s):  
Mingjiang Sun ◽  
Silvia C. Finnemann ◽  
Maria Febbraio ◽  
Lian Shan ◽  
Suresh P. Annangudi ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Outer Segment ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Photoreceptor Outer Segment

scholarly journals The Influence of Hepatocyte Growth Factor During Outer Segment Phagocytosis by Retinal Pigment Epithelium

2011 ◽  
Vol 17 (S2) ◽  
pp. 306-307
Author(s):  
J Blaize ◽  
J Tachjadi ◽  
W L'Amoreaux
Keyword(s):  
Growth Factor ◽  
Retinal Pigment Epithelium ◽  
Hepatocyte Growth Factor ◽  
Outer Segment ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Hepatocyte Growth

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Membrane turnover in rod photoreceptors: ensheathment and phagocytosis of outer segment distal tips by pseudopodia of the retinal pigment epithelium

1987 ◽  
Vol 230 (1260) ◽  
pp. 339-354 ◽  
Keyword(s):  
Retinal Pigment Epithelium ◽  
Outer Segment ◽  
Excitatory Amino Acid ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Ultrastructural Changes ◽  
Membrane Turnover ◽  
Rhodamine Phalloidin ◽  
Cytoplasmic Matrix ◽  
Rpe Cells

We have documented the ultrastructural changes that occur within the photoreceptor outer segment and the retinal pigment epithelium (rpe) during photosensitive membrane turnover. We employed an in vitro eyecup preparation from Xenopus laevis in which a large shedding event was induced by adding the excitatory amino acid l-aspartate (Green-berger & Besharse I985; J . comp . Neurol . 239. 361-372). We found that during L-aspartate-induced shedding the rpe cells formed. on their apical domains, previously undescribed processes that were directly involved in disc phagocytosis. These processes are structurally similar to processes formed by macrophages during phagocytosis and are accordingly referred to as pseudopodia. Pseudopodia were distinguishable from the apical villous process normally extended from the rpe in that they were closely applied to the surface of the outer segment, had a cytoplasmic matrix of low electron density that was devoid of most cellular organelles and were enriched in thin (7 nm diameter) filaments. Filament size, specific pseudopodial staining with the actin-specific probe rhodamine phalloidin and inhibition of pseudopod formation by cytochalasin D suggested that the thin filaments were composed of actin. Pseudopodial formation also occurs during a normal light-initiated shedding event. However, the low frequency of shedding, the asynchrony of the individual shedding events and the transient appearance of the pseudopodia prevented a full appreciation of their role during normal disc shedding. Associated with massive shedding and pseudopodial formation, there was an increased adherence between retina and rpe. During l-aspartate treatment, the apical portions of the rpe cells partitioned with the distal outer segment during retinal isolation. This effect was directly related to the development of pseudopodia and may reflect alteration of surface features of the rod outer segment (ros)-rpe interface related to phagocytosis. Our observations show that transiently forming pseudo­podia are the organelles of phagocytosis and that they may play a role in disc detachment as well.

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