Extended Data Fig. 2. Examples of well-formed ETiX embryoids, failed ETiX embryoids and cultured natural embryos.

a. Typical day 8 ETiX embryoids judged as developing successfully. b. Typical failed ETiX embryoids at day 8. c. Natural embryos cultured ex utero from E6.5 to E8.5. All structures are stained with DAPI. Morphological features: Hf, Headfolds; H, Heart; T, Tail: All, Allantois. (Some of these samples are also shown in the following panels: v in Fig. 4g; vi in 2d; viii in Ext. Data Fig. 7g; xi in Ext. Data Fig. 4a; xii in Ext. Data Fig. 5c; xiii in Fig. 4b; xvi in Fig. 4h; and xvii in Fig. 2e).