A common method for determining the percentage of viable cells in
a sample is to stain the sample with a mixture of ethidium and acridine
orange, and to observe the sample under a fluorescence microscope. In
flow cytometry, a sample is usually counterstained with propidium in order
to exclude dead cells.
I have been comparing these two methods, and have found that the
propidium-based method in flow always gives me a higher percentage of dead
cells than the ethdium/acridine orange microscope method.
Any ideas why this is so?
- John Ladasky
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