Kinetic study of cell death decisions during trophectoderm commitment.

We measured total transcription in the inner cell mass (ICM) and the trophectoderm (TE) of the human embryo to understand the mechanisms underlying TE commitment. We describe here identification of a cell death program functioning in lineage commitment in embryonic stem cells of the human embryo. Bax, Bok and Bcl6 were central effectors modulated most significantly. Other apoptotic effectors, like AEN and genes of the annexin family were affected. We also observed changes in caspase expression during execution of TE commitment. Casp3 was most closely associated with the TE differentiation program. Casp6 and Casp7 expression was also modulated during this specific phase of human embryonic development.