Mouse pluripotent stem cells at a glance.

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of an embryo at the blastocyst stage. They are characterised by the ability to proliferate indefinitely (or selfrenew) in vitro while maintaining pluripotency, i. e. the capacity to differentiate into germ cells and a broad number of cell types that originate from the three primary germ layers endoderm, mesoderm and ectoderm. Defining the identity of embryonic pluripotent stem cells has been a main focus for the stem cell field since the derivation of the first mouse ESCs (mESCs) in 1981 (Evans and Kaufman, 1981; Martin, 1981). Indeed, mESCs could simply be the