Oil Red O
Classification: lipid stain
Mechanism of staining: selective solubility
Purpose: stain lipids
Control tissue: any tissue containing fat
Properly Stained Slide
Lipid & lipofuchsin: red
Nuclei: blue
REAGENT |
PURPOSE |
MECHANISM OF STAINING |
SOURCE OF ERROR |
Oil Red O |
Primary stain – demonstrates lipids (progressive stain) |
Selective solubility. Tissue neutral lipids are more soluble
than 60% isopropanol. |
Omitted: Lipids will not be demonstrated. |
Too short: Lipid staining will be less
intense. |
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Too long: Will not affect staining. |
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60% Isopropanol |
Removes background staining |
Organic solvent used to make a collodial suspension with Oil Red O. |
Omitted: Pink background staining. Isopropanol rinse is optional. |
Too short: Will not affect staining. |
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Too long: Will not affect staining. |
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Harris hematoxylin |
Counterstain – stains nuclei and other tissue components |
Ionic bonding |
Omitted: Nuclei and other tissue elements
will not be demonstrated. |
Too long: May obscure lipid staining. |
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Too short: Nuclei and other tissue elements
will be obscured. |
Special Considerations
Tissues cannot be fixed with alcoholic fixatives that will dissolve the lipids needing to be visualized. Cryostat tissue sections are often used.
Permount cannot be used to affix the coverslip as it will also dissolve lipids. An aqueous mountant such as glycerol jelly can be used. Glycerol jelly is warmed to 37 degrees celsuis in order to liquify it for application. The edges of a coverslip can be lined with nail polish to further protect the slide.
Pressure to the coverslip after mounting will cause the lipids to run together, obscuring their origin in the tissue.
References
Officer B. HIML251 Lecture notes: Congo Red, Toluidine Blue, and Oil Red O, March 11, 2009
Pathology Outlines- Case of Week. 2008. [cited 2009 April 6]. Available from http://pathologyoutlines.com/caseofweek/case200638image5.jpg