Comparison of transgene and VE-cadherinexpression. Costaining of a E13.5 embryo section with anti-CAT (A) and anti–VE-cadherin (B) antibodies showed an identical expression pattern, as illustrated here for the oral area. In situ hybridizations, performed with either the CAT (C,E) or the VE-cadherin(D,F) probe on adjacent sections (10 μm), confirmed specific endothelial expression of CAT at the transcript level. (C,D) Oral area; (E,F) hindlimb; scale bars represent 100 μm.