COS7 cells giving me problems - (Jun/30/2011 )

I am using COS7 cells to do transfection and immunofluorescence experiments. But sadly, my COS cells have started to look gross. I see some spots around the cells. Please see attached pic and help me figure out what could be the reason for my cells looking like this. It looks like something is coming out from the inside of the cell or the cell membrane is rupturing??? Any suggestions/comments?

Thanks!!

It is a bit hard to tell from the picture, but those could be cellular inclusion bodies, mitochondria, bacteria...

If your cells are not behaving as you would expect you should throw them out and get some fresh ones up... you should do this at least every 10 passages or so anyway, as sustained periods in culture can cause selection of the cell line for different phenotypes.