I'm trying to compare cell diameters and volumes of different cell types using an automated cell counter Scepter (Millipore). The counter draws histograms of diameters and volumes on the screen and calculates mean values (for example, 17.03 um and 2.59 pl). The distribution of diameters looks normal and the distribution of volumes is skewed.
Also the device allows to download the file containing original data in csv format. When I calculated the mean of cell volumes and drew the histogram I found a perfect match with the previously described results. But cell diameters were different. The mean was 9.05 (instead of 17.03) and the distribution of diameters was skewed like the distribution of volumes instead of being normal.
I also found out that diameters and volumes are related according to the formula: volume = 0.8105*diameter -4.751.
Has anyone found out how the device calculates cell diameters?
Thanks.
P.S. An example file is attached.
Hi,
I have downloaded your sample file, and confirmed what you say are all true.
Something must be wrong with the instrument.
You should definitely contact Millipore tech support.
Cheers!
Thank you, Shin-Ichiro!
I'm still waiting for response of tech support...
Hi! Did you get an answer from tech support? I might have a similar issue
Hi, Nadege!
They didn't answer. Maybe I used wrong e-mail or something. I'm in the middle of vocation and I'm going to return to this question in August. I'll inform you about the answer.
Hi Iliya,
I did get to talk to them. It may be due to a broken pin on the sensor. If you look (without opening anything in the sensor (where you insert the sensor tip), you may be able to see if the sensor pins are damaged (they should all be the same size and height and should not be bent). Have a good vacation!
Thank you, Nadege!
I'll have a look at sensors when I get back at work.
But I think the problem lies not only in sensors. In this case incorrect data would appear on the screen of Scepter too. I suggest there is a bug in computer program which saves csv files. Maybe diameters in csv file come from the wrong value which is used for volumes calculations while the correct value is used for calculations of histograms which appear on the screen.
Good luck!
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