Fig. 3. Deletion of intron 2 leads to loss of ß-gal expression during early embryogenesis. (A-E) Whole-mount X-gal staining of Ecad-In2flox embryos between E6.5 and E10.5. (F,G) Paraffin sections of whole-mount stained Ecad-In2flox embryos. Transverse section at E7.5 (F) indicates expression in ectoderm and endoderm, but not in mesoderm. Expression levels appear higher in posterior ectoderm. Sagittal section at E10.5 (G) shows high-level ß-gal expression in pharynx and gut epithelium. Low-level expression in surface ectoderm is not visible in sections at this stage. (H-L) Whole-mount X-gal staining of Ecad-In2floxdel embryos between E6.5 and E10.5. Expression is only observed at low levels in AER and yolk sac at E10.5 (L). (M,N) Paraffin sections of whole-mount stained Ecad-In2floxdel embryos. No ß-gal expression is observed in sections of E7.5 embryos (M, transverse section) or inside of E10.5 embryos (N, sagittal section). (O) Semi-quantitative (upper panel) and real-time PCR (lower panel) of embryonic cups of Ecad-In2flox (+/flox) and Ecad-In2floxdel (+/del) embryos, similar to Fig. 2. A reduced signal is observed in +/del samples. For each PCR, a control without reverse transcriptase (-RT) is given. Transcript amounts were calculated from real-time PCR to be 85% reduced in Ecad-In2floxdel samples (lower panel). Scale bars: 100 µm in A,H; 250 µm in B,C,G,I,J,N; 500 µm in D,E,K,L; 50 µm in F,M.