Fig. 4

On E16. The anal membrane ruptured and rectum communicated with the outside. Rare TBX4 positive cells were expressed in the epithelium of the distal rectum in normal group (a, b). The fistula between the urethra and rectum of the ARM embryos still existed, and only sporadic TBX4-immunopositive cells were distributed in the epithelium of the rectum and the fistula (c, d). Red rectangles in a and c are shown at higher magnification in b and d ×40 (a). ×100 (c). ×400 (b, d). Black arrowhead: positive cells. F Fistula, U urethra, R rectum