LacZ staining in mice embryos carrying the Gfi1-lacZ BAC identifies the sites of endogenous Gfi1 expression. (A) Vista plot of sequence conservation between mouse and human across the Gfi1 locus. The 148-kb region contained in the Gfi1-lacZ BAC, in which the lacZ gene has been inserted at the translational initiation ATG codon of Gfi1 by homologous recombination, is indicated below. (B) X-Gal-stained E11.5 embryos carrying the Gfi1-lacZ BAC showing lacZ expression in the eye, nose and ear (i), somites and mammary glands (ii), limbs (iii), and neural tube (iv). (C) Paraffin tissue sections from an E11.5 embryo showing lacZ expression in the dorsal aorta (DA), fetal liver (FL), somites, snout, stomach, and around the eye.