Fig. 3.

BET activity is required for the pluripotency of blastula stem cells. (A,B) In situ hybridization examining expression of mesodermal markers (xbra and myoD1; A) and endodermal markers (endodermin and sox17b; B) in blastula explants induced with activin and treated with vehicle or IBET (250 µM). Embryos were treated at the two-cell stage, then explants were grown in culture with sibling embryos for staging purposes and collected at stage 11.5 (mid-gastrula) for xbra, endodermin and sox17b expression and stage 18 (late neurula) for myoD1 expression. (C) In situ hybridization examining expression of neural markers (nrp1 and sox11) in blastula explants induced with chrd mRNA and treated with vehicle or IBET. Embryos were treated at the two-cell stage and explants were collected at stage 18 (late neurula). Scale bars: 250 μm.