Fig. 6. Apoptosis during normal GT development. (A) Sectioning of 10.5 dpc embryos revealed apoptotic cells in the epithelium of the outermost part of the urogenital sinus before GT outgrowth. (B) At 11.5 dpc, apoptotic cells were found in the urethral epithelium and mesenchyme in the distal region of the GT. The GT region is marked by a white line. (C) Apoptosis was mainly localized to the mesenchyme in the distal region adjacent to the urethral plate epithelium at 13.5 dpc. (A) Transverse section. Scale bars: 62.5 µm in A; 250 µm in B; 312.5 µm in C.