Human trophectoderm cells are not yet committed.

Study Question: Are human trophectoderm (TE) cells committed or still able to develop into inner cell mass (ICM) cells?

Summary Answer: Human full blastocyst TE cells still have the capacity to develop into ICM cells expressing the pluripotency marker NANOG, thus they are not yet committed.

What Is Known Already: Human Day 5 full blastocyst TE cells express the pluripotency markers POU5F1, SOX2 and SALL4 as well as the TE markers HLA-G and KRT18 but not yet CDX2, therefore their developmental direction may not yet be definite.

Study Design, Size, Duration: The potency of human blastocyst TE cells was investigated by determining their in vitro capacity to develop into a blastocyst with ICM cells expressing NANOG; TE cells were isolated either by aspiration under visual control or after labeling with fluorescent 594-wheat germ agglutinin.