Blastocyst contraction

Blastocyst contraction was defined according to the methodology described by Marcos et al. (2015) as an event in embryo development during blastulation, when the perivitelline space is observed again by the retraction of TE cells (Fig. ​(Fig.1).1). Contraction pattern was studied from the time when the TE cells started pushing on the zona pellucida (ZP), as described previously by Bodri et al. (2016). The presence and number of embryo contractions was annotated for each embryo individually and analysed blindly to the corresponding genetic result.

Embryo contraction presence during blastulation. Contraction behaviour is annotated during blastulation, from the moment when the trophectoderm cells start pushing towards the zona (Fig. 1 100.6 h). Contraction presence was described by the retraction of TE cells (Fig. 1 102.3 h). Embryo biopsy is performed on fully expanded blastocysts with hatching cells (Fig. 1 117.3 h)