Dear all

I am having some problem in culturing mES on STO. When I cultured mES on STO, most of the ES colonies are normal but there are several colonies which have gone little bit Differentiation most probably primitive Endoderm (as these cells have polygonal shape and bright border). And after that if i subculture them with STO or without STO, this nature of differentiation become more prominent. I use STO which Passage number is within 17 to 20. I use ES qualified FBS and LIF 1000 U/ml.

I do not know the reason . Please give me some information.

Regards
Chowdhury, Mohammad Mahfuz
D1, University of Tokyo