ABSTRACT
ESCs are the in vitro derivatives of the inner cell mass of the blastocyst. ESCs have the attributes of self-renewal and pluripotency. The fi rst ESC lines were established from mouse blastocysts in 1981 (Evans and Kaufman 1981, Martin 1981). The mouse ESCs (mESCs) grow on a feeder layer of non-proliferating mouse fi broblasts and maintain their undifferentiated state in the presence of leukemia inhibitory factor (LIF). mESCs give rise to germ-line chimaeras, and are able to do tetraploid complementation, two major criteria for testing the pluripotent capabilities of mESC lines (Bradley et al. 1984).
