Lineage commitment in the mammalian preimplantation embryo

Summary Early embryo mortality during the first two weeks of development is an important factor in the decreasing fertility of dairy cattle. During this period the embryo needs to correctly establish the first three lineages, namely epiblast, hypoblast and trophoblast so as to survive. The morphological and molecular events underlying these lineage decisions are discussed, drawing on information derived predominantly from mice and cattle. TE be traced the DiI TE donor cells maintain their original fate and contribute only to TE, they would be considered to have been committed to this fate at the stage that they had been isolated. If they were to contribute to both ICM and TE, they would be considered to have been uncommitted.