scholarly journals Studies on microperoxisomes. VII. Pigment epithelial cells and other cell types in the retina of rodents.

1975 ◽  
Vol 65 (2) ◽  
pp. 324-334 ◽  
Author(s):  
P M Leuenberger ◽  
A B Novikoff
Keyword(s):  
Epithelial Cells ◽  
Vascular Endothelial Cells ◽  
Smooth Endoplasmic Reticulum ◽  
Photoreceptor Cells ◽  
Cell Types ◽  
Vascular Endothelial ◽  
Pigment Epithelial ◽  
Large Numbers ◽  
And Storage ◽  
Pigment Epithelial Cells

The pigment epithelial cell of the retina actively participates in two aspects of lipid metabolism: (a) the fatty acid esterification of vitamin A and its storage and transport to the photoreceptors, and (b) the phagocytosis and degradation of the lipoprotein membrane disks shed from the photoreceptor cells. Study of the pigment epithelial cells of adult albino and pigmented rodents has revealed the abundance of an organelle, microperoxisomes, not previously known to exist in this cell type. The metabolism, transport, and storage of lipids are major functions of other cell types which possess large numbers of microperoxisomes associated with a highly developed smooth endoplasmic reticulum. Microperoxisomes were encountered, but relatively rarely, in Müller cells and vascular endothelial cells. A tubular system in photoreceptor terminals is reactive in the cytochemical procedure used to visualize microperoxisomes.

scholarly journals 5′-Nucleotidase in Rat Photoreceptor Cells and Pigment Epithelial Cells Processed by Rapid-freezing Enzyme Cytochemistry

1998 ◽  
Vol 46 (9) ◽  
pp. 1091-1095 ◽  
Author(s):  
Toshihiro Takizawa
Keyword(s):  
Epithelial Cells ◽  
Photoreceptor Cells ◽  
Striking Difference ◽  
Rapid Freezing ◽  
Rod Outer Segments ◽  
Enzyme Cytochemistry ◽  
Apical Process ◽  
Pigment Epithelial ◽  
Outer Segments ◽  
Pigment Epithelial Cells

This report describes the subcellular distribution of 5′-nucleotidase (5′-NT) in rat photoreceptor cells and pigment epithelial cells processed by rapid-freeze enzyme cytochemistry. There was a striking difference in the ultrastructural localization of 5′-NT activity between rod outer segments after freeze-substitution fixation and conventional fixation. By rapid-freezing enzyme cytochemistry, 5′-NT activity was localized in the extradiscal space of intact nonvacuolated discs, whereas by conventional cytochemistry it was shown in the intradiscal space of artifactual vacuolated discs. In the freeze-substituted retinal cells, an appreciable difference in functional 5′-NT molecules was also found. The soluble 5′-NT on the cytoplasmic side of the disc membrane was vital in the rod outer segments, whereas the membrane-bound ecto-5′-NT on the exoplasmic (external) surface of the apical process was active in the pigment epithelial cells. Rapid-freezing enzyme cytochemistry should be worth employing as a method to reveal the fine localization of enzyme activity at the level of cell ultrastructures, which are poorly preserved by conventional fixation, and should provide information approximate to that in living cells.

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