embriyoid body formation is used for embriyo generated in vitro situation. it is grown in vitro and in the stage of blastocyste inner cell mass isolated and it is grown in medium for providing ıts immortal division. after it is providen it is exposed to some growth factors and others respectively for obtaining differantation to which cell we want. there are more signaling factors which triggers a cell for differantiating and they are waiting for to be explored.