Phagocytosis of rod outer segments by human iris pigment epithelial cells in vitro

1998 ◽  
Vol 236 (10) ◽  
pp. 753-757 ◽  
Author(s):  
G. Thumann ◽  
Karl Ulrich Bartz-Schmidt ◽  
Klaus Heimann ◽  
Ulrich Schraermeyer
Keyword(s):  
Epithelial Cells ◽  
Rod Outer Segments ◽  
Pigment Epithelial ◽  
Outer Segments ◽  
Human Iris ◽  
Pigment Epithelial Cells

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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