Fig. 1. T-Cre-mediated activation of the R26R reporter allele. (A) Schematic representation of the T-Cre transgene. (B) Cre-mediated recombination of the R26R reporter deletes the neo^R fragment thereby restoring ß-galactosidase activity (ß-Gal). (C-L) Whole-mount images (C-F,I) or sections (G,H,J-L) of T-Cre; R26R embryos stained for ß-Gal. (C) Lateral view of an E7.5 embryo. Horizontal bar indicates the extraembryonic/embryonic border. (D) Ventral view of an E8.0 embryo, demonstrating reduced staining in the node region. (E) Dorsal view of an E8.5 embryo. (F) Lateral view of an E9.0 embryo. Dotted lines indicate transverse sections shown in panels G and H. (I) Lateral view of an E10.5 embryo. Dotted lines indicate sections in panels J and K. (J) Horizontal section through an E10.5 head. (K) Transverse section through an E10.5 embryo, demonstrating ß-Gal staining in the ectoderm and AER. (L) Section through an E14.5 kidney. 4th, fourth ventricle of neural tube; aer, apical ectodermal ridge; al, allantois; ß-ac. polyA, DNA fragment containing the ß-actin polyA sequences; cm, cephalic mesenchyme; fb, forebrain; gt, gut; hb, hindbrain; ht, heart; ln, lens; mb, midbrain; mv, mesencephalic vesicle; nc, notochord; nd, node; nt, neural tube; pro, promoter; ps, primitive streak; se, surface ectoderm; so, somites.