LIF (leukaemia inhibitory factor) is commonly used to maintain mouse embryonic stem cells
in an undifferentiated state. These cells spontaneously differentiate when allowed to
aggregate in the absence of LIF, forming embryoid bodies in which early embryonic cell
lineages develop. Using embryoid bodies cultured in the presence and absence of LIF, we
show that although LIF inhibited the development of visceral and parietal endodermal cells,
it did not affect the differentiation of the primitive endodermal cell precursors of these …