Fig. 2. X-gal staining of Lama1 Trap and Lamb1 Trap embryos. Whole Lama1 Trap embryos are shown at E9.5 (A,C), E11.5 (D) and E13.5 (E). A control E9.5 littermate stained in X-gal is also shown (B). There is intense X-gal staining in the central nervous system and in presomitic mesoderm (arrowhead in C, black arrow in D, white arrow in E). Once formed, somites soon lose X-gal reactivity (black arrow in C). (F) The urogenital region was dissected out of an E16.5 male Lama1 Trap embryo and then stained with X-gal. Prominent staining of the vas deferens (white arrow) and punctate staining in kidneys was observed. Whole Lamb1 Trap embryos are shown at E11.5 (G) and E13.5 (H).