Embryos were cultured on MEF, STO, STO1 (STO cells were inactivated by mitomycin and frozen and thawed when needed) and PEF feeders.

• 比较了不同的饲养层对昆白小鼠ES细胞分离克隆的影响:分别以MEF、STO、经丝裂霉素C处理后冷冻再解冻的STO和PEF作为饲养层;