TE Quality in Blastocysts
To select the best blastocyst for transfer, three morphological parameters have routinely been used, i.e. 1. The degree of cells expansion, 2. the appearance of both outer part of the cell mass - the trophectoderm (TE) and 3. the inner cell mass (ICM). Although it has been shown that blastocysts with highest scores for all three parameters achieve highest implantation rates, their independent ability to predict pregnancy outcome remains unclear.
Trophectoderm is the first cell type that emerges during development and plays pivotal roles in the first step of reproduction in a placental of baby. The trophectoderm develops into the placenta and construct the placenta.
Like the ICM, trophectoderm quality depends on the number of cells and how cohesive and packed together they are. The trophectoderm is like an igloo which needs many blocks of ice that fit together well otherwise it may fall apart. The same thing for a baby that going into this world.
All three parameters have a significant effect on live birth however, once adjusted for known significant factor, it was shown that Trophectoderm Grade is the only statistically significant independent predictor of live birth outcome.
A new study has shown, for the first time, the predictive strength of Trophectoderm Grade over inner cell mass (ICM) for selecting the best blastocyst for embryo transfer. It may be that, even though inner cell mass (ICM) is important, a strong Trophectoderm layer is essential at this stage of embryo development, allowing successful hatching and implantation of embryo.