Sexually dimorphic expression of Mafb during GT development. (A) Image of anti-MAFB pAb staining (brown) that represents MAFB expression in male GT mesenchyme adjacent to the urethral plate (square) at E16.5. (B–G) Appearance of the developing GT of MafbGFP/+ male mice (B, D, and F) and MafbGFP/+ female mice (C, E, and G). GFP fluorescence indicates the Mafb-expressing region (red arrow in B, D, and F). (H–M) Expression pattern of Mafb in the developing GT of male (H, J, and L) and female (I, K, and M) embryos. Its expression was detected by GFP immunostaining. Yellow arrows in H, GFP-positive GT mesenchymal cells. Insets in H–M, higher magnification of the GT mesenchyme adjacent to the urethral plate.