cell confluence in cell cultures - myoblast c2c12 in particular (Feb/01/2011 )

Hi to all. I'm a grad student and I work on cell cultures. I'd like to ask you one thing about the tecnique, I hope you can help me to understand sorry if my english is not perfect.

I work with the myoblasts cell line c2c12. I know that cells must not reach confluence becouse otherwise they begin differentiate. furthermore they must be at 60-80% confluence before passing or splitting them.

Does the term "confluence" mean that cells cover the entire surface of the plate?
How can I see when cells reach 60-80% confluence? Do you know if I can find somewhere some images about cell coltures at different grade of confluence?

Thank you very much for your precious help!

Correct, confluency is the amount of culture surface that is covered by cells. Your best bet for learning how to assess the confluency is to get an experienced person to look at your cells and tell you how confluent they are and learn from that.

You can think of it like this... 25% confluent is a quarter of the surface area covered by cells, 50% is half the area and 75% is 3/4 of the area.

ok thank you for your help