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Normal cells or contamination?! - (Oct/30/2013 )



So I was checking my cells and there appeared to be very large cell-aggregates, where the aggregated cells were smaller than the normal cells. The light of the microscope went through them more than the normal cells, so they appeared to be yellowish. I researched images on the cells (NTera-2 Cells), and found that the cells have a tendency to differentiate without the induction by retinoic acid (the only article I found that mentioned that they could naturally differentiate). The clusters appear like stem cell spheres (neurospheres). 


I checked the cell media, and it did not appear cloudy, nor did I see bacteria. 

The following images are not my cell images.

What are the small black dots, they look like bacteria?

What contamination could that be?


Your google links don't work for me (they give the whole search results, not a specific picture)
If the clusters appear like neurospheres, surely they are less differentiated though ?


Tabaluga,, here is the specific link.


I am not sure what is going on with my cells, some are normal NT2 cells, others are differentiated into neuron-like cells, and then I have the small cells clumped together that are yellowish/see-through. Those cells which are isolated (identified by their yellowish color) appear to get larger over time. They get larger, but still have a circle-cell shape. Some though, have neuron-like axon/dendrites.


I was searching embryonic stem cells, which can be simulated with NT2 cells, and found that EBs without the feeder layers tend to clutter together (yet don't form a sphere), just like my cells. My cells are adherent and do not have feeder layers. It's weird, every time I look in the culture, the cells look different, but they don't look like bacteria.


the links don't look for me either, but do your "aggregates"  consist of clearly visible small cells, clustered together, or are they more like one large round more or less transparent entity? If they are a cluster, I'd suspect they are made of dead cells. If they are more uniform, perhaps they represent cells that tried to divide, but failed? 


Pictures of my cells are found on