Extended Data Figure 2.

The ex vivo paused epiblast retains naïve pluripotency markers and is devoid of apoptosis. It is possible that the signs of apoptosis in the TE contribute to the eventual demise of mTor-inhibited blastocysts after prolonged culture. Immunofluorescence images of untreated vs. paused blastocysts for Nanog (a), Rex1 (b), cleaved Caspase 3 (c) and cleaved Parp1 (d). Oct4 staining is shown in all cases as a marker of the ICM. Note that the ubiquitous staining pattern for Rex1 is as expected³⁶. Scale bar = 50 μm. The number of embryos analyzed (n) is indicated.