The KRT8 is considered to be a predictor of embryo survival (Ghanem et al., 2011) and KRT8 and SFN were found to be upregulated in TE cell populations during early bovine blastocyst growth to Day 7 and Day 8.75 (Negrón-Pérez et al., 2017), and we also found KRT18 mis-expressed in clone embryos (Somers et al., 2006). The other genes are all upregulated in the placenta portion of the embryo. The genes in the 2nd component (red) with PLS weight less than −0.013 are CCNB1, KLF4, OTX2, SMAD3, SOX2, SPIC, and STAT3. All these genes are upregulated in the inner cell mass cells (except possibly CCNB1). The gene in the first component (blue) with PLS weight greater than 0.013 is PTGS2, and no genes in the first component (blue) have a PLS weight less than −0.013. The PTGS2 appears in each component and is positively correlated with embryo size, which is consistent with gene expression in Day 15 embryos after ET on Day 7 (Shorten et al., 2018) and Day 7 embryos in cows that become pregnant (Ghanem et al., 2011). The PTGS2 is also the best single gene predictor of embryo size on Day 7. This is also consistent with the role of PTGS2 on increasing embryo survival and promoting ED development and embryo elongation during development to both Day 8 and Day 15 (Nuttinck et al., 2017).Moraes et al. (2018) also identified that PTGS2 was a critical enzyme that may play a central role in gene expression networks in high- and sub-fertile conceptuses. The role of embryo stage (M, TM, EB, B, XB) on the gene expression of nanostring genes with a mean log10 gene expression greater than 0.6 is shown in Supplemental Figure S15 (https:// doi .org/ 10 .3168/ jds .2017 -14306) where PTGS2 exhibits a 25-fold increase in expression between morula to expanding blastocyst stages.