HDAC inhibition leads to aberrant expression of multiple lineage markers. (A-C) In situ hybridization examining the expression of lineage markers: endoderm (sox17; A), mesoderm (myod; B) and neural (sox11; C) in aging animal pole explants treated with vehicle or inhibitor (500 nM TSA). Explants were cultured alongside sibling embryos and grown until late blastula (stage 9), mid-gastrula (stage 11) and neural plate (stage 13) stages. (D,E) qRT-PCR examining markers of specific lineages [endoderm (sox17, vegt), mesoderm (myod, xbra) and neural (olig2, sox11)] in pluripotent and aged animal pole explants following treatment with vehicle or inhibitor (500 nM TSA) (*P<0.05, **P<0.01, ***P<0.005). Explants were cultured alongside sibling embryos until late blastula (stage 9) and neural plate (stage 13) stages. Scale bars: 250 μm.