Fig. 3. Expression patterns of transgenes directed by distal (–3303/+196) and proximal (–637/+196) regulatory regions of Bop at E11.5. Whole-mount views of F0 transgenic embryos at E11.5 with construct 1 (–3304/+196; A-D) and construct 2 (–637/+196; E-H) are shown (see constructs in Fig. 2). (A,B,E,F) Left and right sides of embryos are shown. (C,D,G,H) Histological sections. (C,D) Robust expression of construct 1 is seen in the ventricular and atrial chambers of the heart and somite myotomes. Identical expression patterns were seen in 6 out of 7 embryos with this construct (data not shown). (G,H) Construct 2 is expressed specifically in the right ventricular chamber and somite myotomes. Identical expression patterns were seen in 5 out of 5 embryos with this construct (data not shown). m, myotomes; oft, outflow tract; ra, right atrium; rv, right ventricle; lv, left ventricle; la, left atrium.