Fig. 2. Expression patterns of selected genes, as determined by in situ hybridisation in wild-type and ß-catenin mutant embryos. Whole-mount in situ hybridisation (A,B,I-L,N), in situ hybridisation of sections of embryos in utero (C-H,O-R), and transverse section through primitive streak region (M) are shown. Arrows in M indicate cells that leave the primitive streak to become mesoderm. Arrow in Q indicates expression in visceral endoderm.