Defective primitive streak formation in Hexd^act/+ mutants.

(A–C) Eomes, T and Cripto expression in wildtype and Hexd^act/+ mutant embryos at 6.5dpc. (D–N) Expression of Eomes, T, Chordin, Noggin, Foxa2, Wnt3, Tbx6, Fgf8, Snail, Sox17 and Cerl in control and Hexd^act/+ mutant embryos at 7.5dpc. Hexd^act/+ embryos with normal expression: T (6.5dpc) n = 7/7; Cripto n = 9/9 Wnt3 n = 11/11; Tbx6 n = 13/13; Foxa2 n = 8/8; Cerl n = 14/14; Sox17 n = 14/14. Hexd^act/+ embryos with reduced or lost expression Eomes (6.5dpc) n = 2/11; Eomes (7.5dpc) n = 3/18; T (7.5dpc) n = 3/14; Chordin n = 2/11; Noggin n = 6/15, Fgf8 n = 5/17; Snail n = 3/14. (O) T expression in control and (O′) Hexd^+/−;Sox2Cre^+/− embryos at 7.5dpc (n = 16/16). Blue arrow indicates the anterior primitive streak in D and E. Scale bar 90 µm.