TUNEL assay - explanation of quantification? (Apr/23/2008 )

Hi everyone,
I am doing TUNEL assay by millipore and unlike most everyone here I am not doing flow but am doing IHC. I do my counterstain with PI after treatment with TdT working strength enzyme. My question is how do I quantify my data? When I look at my chamber slide I see more fluorescence in my pro-apoptotic cells which is great but I don't know how to put that into data. I have read papers using similar assays but they do not really explain how they do it? I feel like this is a simple question but want an experienced answer instead of guessing. Thanks in advance!

I've never used TUNEL for IHC, but I've seen many papers use the apoptotic index, which is basically just looking at 400 cells in 4 different fields and counting the number of them that are TUNEL positive, expressed as a percentage.