No contamination! The cells look like they have lipid droplets. Oil Red O or DiI staining would confirm this. Some breast cancer cells can become lipid-laden foam cells.

I would say that this is not contamination. When bacteria appears its used to see black points moving. Also does not look like yeast. Has the medium turned to different colour or get turbidity?

Adrián Puerta

Thank you for your answer.

When i see the flask, medium didn't change color and turbidity. (few floating debris cells)

I wonder the circle in cells, my superior said he think contaminated in cells.