Fig. 7. Increased cell death and decreased cell proliferation in Shh-/- mutant GT. (A-D) Apoptosis in 10.5 dpc (A,B) urogenital sinus and in 11.5 dpc (C,D) GT of wild type (A,C) and Shh-/- (B,D) embryos was examined by TUNEL analysis. Striking increase of apoptosis was found in the urethral epithelium of Shh-/- mutant (B,D) and the results are summarized in G. (E,F) Expression of Bmp4 in 10.5 dpc wild type (E) and Shh-/- (F) before GT outgrowth. In contrast to wild type, where expression is found only in the urogenital sinus mesenchyme, Bmp4 is expressed in the epithelium of Shh-/-. (H) Cell proliferation in 10.5 dpc urogenital sinus and 11.5 dpc GT of wild-type and Shh-/- embryos were determined by measuring BrdU incorporation. Shh-/- GTs showed a significant decrease in cell proliferation when compared with those of wild-type embryos. Six embryonic specimens were analyzed for wild-type and Shh mutants, and each sample was analyzed using four serial sections (G,H). (A-F) Transverse sections. Scale bar: 62.5 µm.
