Unidentifiable contaminant. Image attached - (Apr/12/2012 )

Hi everyone,

Can you help me identify the contaminant in this phase contrast image? I'm culturing primary neurons from chick. I use Pen-strep, and L15 and methylcellulose supplemented with glucose, FBS, and NGF. The contaminant does not move, and it does not increase in number over days, leading me to believe it might not be something growing or living?

Thanks!

Hard to say for sure, but it looks like cell debris from dead cells.

Thanks, Bob. It wasn't cell debris, I don't think, because filter-sterilising the FBS reduced these dots. For a moment there I was worried it was something like Achromobacter, but it doesn't grow or move. I'm guessing it's just clumped up stuff from serum.