Effects of thyroid hormone on human preimplantation embryos

We found that the exposure of human preimplantation embryos to triiodothyronine (T3) has a profound impact on gene transcription only in the cells of inner cell mass (ICM) and no effect on cells of trophectoderm (TE). A total of 30 embryos at the two pronuclear (2PN) stage were used for the experiment; fifteen embryos were exposed to 10-7 M T3 till blastocyst stage and the remaining 15 embryos acted as controls.