Fig. 2. Functional conservation of the 88 bp homology region-c (HR-c) element. X-gal staining of transgenic embryos at 9.5 dpc carrying three copies of HR-c from mouse (A,D), chicken (B,E) and zebrafish (C,F). Transverse sections through the spinal cord at the level of the forelimb of representative embryos revealed strong floor plate and notochord expression from mouse (D) and chicken (E) but not zebrafish (F) DNA. The ectopic staining from Rc11 was seen in all six transgenic embryos. The broken line in D,E mark the boundary between the floor plate and notochord.