Fig. 7. Expression patterns of genes related to Nodal signaling. (A,D,G,J,M,P,S) Expression of cryptic was examined in wild-type mouse embryos by whole-mount in-situ hybridization. Expression was bilateral in LPM at E8.2 (red arrowheads in A) but was not detected at E9.0 (D,G,J) or E9.5 (M,P,S). (B,E,H,K,N,Q,T) Nodal expression was examined by X-gal staining of Nodal^lacZ/+ embryos. Staining was apparent in left LPM at E8.2 (B), was detected at a low level in the heart region containing the common cardinal vein and vitelline vein at E9.0 (E,H,K) and was not observed at E9.5 (N,Q,T). (C,F,I,L,O,R,U) Foxh1 expression was examined by X-gal staining of embryos expressing a Foxh1-lacZ transgene. Staining was apparent in LPM and heart primordial cells at E8.2 (C) and was evident in the heart, but not in the common cardinal vein and vitelline vein, at E9.0 (F,I,L) and E9.5 (O,R,U). Transverse sections were prepared after whole-mount in-situ hybridization (G,J,P,S) or X-gal staining (H,I,K,L,Q,R,T,U). Black and yellow arrowheads in D-U indicate the region that corresponds to the common cardinal vein and vitelline vein and in which asymmetric Pitx2 expression persists in Pitx2^ASE/ASE embryos. Scale bars: 200 µm.