[Expression of LIF gene during early development of mouse embryo]

Leukemia inhibitory factor (LIF) has the ability to maintain the development potential of pluripotent embryonic stem cells, suggesting that this factor might play an important role during mouse embryogenesis. By whole mount in situ hybridization on early mouse embryos, we have examined the expression pattern of the LIF gene from the two cell stage to the preimplantation blastocyst with the following results. (1) LIF transcripts were detected at all stages before implantation, but the highest level of LIF mRNA expression occurred in the blastocyst stage. (2) For the cleavage stages of mouse embryo, there was no significant distinction of the LIF gene expression level between blastomeres, but a strong signal was detectable in the cells which surrounded the blastocoel cavity of the blastocyst and most of them belonged to future extraembryonic tissues. These results suggest that a principal function of LIF in vivo may be to regulate stem cell population and to play an important role in the implantation of the blastocyst.