Fig 2: Spatiotemporal distribution of caudal-type homeobox proteins during gestation week 9.During gestation weeks 9, the anorectal epithelium was positive for CDX1 and CDX4, and CDX1 immunoreactivity decreased gradually from the proximal rectum (R) to the anus. The anal epithelium was positive for CDX2. (R, rectum). Yellow rectangles in (A, D, G, J) are shown at higher magnification in (B, E, H, K), respectively. Red rectangles in (B, E, H, K) are shown at higher magnification in (C, F, I, L), respectively. Original magnification 40× (A, D, G, J), 100× (B, E, H, K) and 200× (C, F, I, L).

Fig 3: Spatiotemporal distribution of caudal-type homeobox proteins during gestation week 4.During gestation week 4, immunoreactivity specific to CDX1, CDX2 or CDX4 was detected mainly in the dorsal urorectal septum (URS), urogenital sinus (UGS) and hindgut (H). The ventral URS and the cloacal membrane (CM) were negative for CDX1, CDX2 and CDX4. (URS, urorectal septum; UGS, urogenital sinus; CM, cloacal membrane; H, hindgut). Red rectangles in (A, D, G, J) are shown at higher magnification in (B, E, H, K), respectively. Green rectangles in (B, E, H, K) are shown at higher magnification in (C, F, I, L), respectively. Original magnification 100× (A, D, G, J), 200× (B, E, H, K) and 400× (C, F, I, L).

Fig 4: Spatiotemporal distribution of caudal-type homeobox proteins during gestation week 6.During gestation weeks 6, the cloacal membrane (CM) was very thin and elongated. CDX1-, CDX2- and CDX4-positive cells were detected mainly in the mesenchyme of the urorectal septum (URS) and hindgut (H). The cloacal membrane (CM) and urogenital sinus (UGS) were negative for CDX1, CDX2 and CDX4. CDX2 and CDX4 immunoreactivity levels were lower compared to CDX1. (URS, urorectal septum; UGS, urogenital sinus; CM, cloacal membrane; H, hindgut). Yellow rectangles in (A, E, I, M) are shown at higher magnification in (B, F, J, N), respectively. Red rectangles in (B, F, J, N) are shown at higher magnification in (C, G, K, O), respectively. Green rectangles in (C, G, K, O) are shown at higher magnification in (D, H, L, P), respectively. Original magnification 40× (A, E, I, M), 100× (B, F, J, N), 200× (C, G, K, O) and 400× (D, H, L, P).

Fig 5: Spatiotemporal distribution of caudal-type homeobox proteins during gestation week 5.During gestartion week 5, CDX1-, CDX2- and CDX4-positive cells were detected mainly in the mesenchyme of the urorectal septum (URS) and hindgut (H). The cloacal membrane (CM) and urogenital sinus (UGS) were negative for CDX1, CDX2 and CDX4. CDX2 and CDX4 immunoreactivity levels were lower compared to CDX1. (URS, urorectal septum; UGS, urogenital sinus; CM, cloacal membrane; H, hindgut). Red rectangles in (A, D, G, J) are shown at higher magnification in (B, E, H, K), respectively. Green rectangles in (B, E, H, K) are shown at higher magnification in (C, F, I, L) respectively. Original magnification 100× (A, D, G, J), 200× (B, E, H, K) and 400× (C, F, I, L).