I see some big regions in embryonic fibroblast culture (red circles in the image), I am very familiar with cells, I marked nuclei with blue circle. These can be dying cells or yeast contamination or what? What do you think?
I think its contamination because most of the time during culture contamination give granular appearance but u can confirm it by increasing the length/duration of culture.
Embryonic fibroblast cultures don't exist. Fetal fibroblasts cultures do. Very little in that photo looks like anything resembling viable fibroblasts. Though nothing in the photo suggests contamination, this does appear to be a horribly degraded culture. How old is the culture in total days since derival? How many passages have they been cultured since their derival?