Fig. 4. Whole gonads (G), together with their mesenteries (GM) dissected from E14.5 embryos. In the Bax^+/+ embryos (A), no ectopic germ cells were found in the gonad mesenteries. Alkaline phosphatase staining was seen in blood vessels in the gonad mesentery (arrow), but not in the PGCs. In Bax^-/- embryos (B-F), large numbers of ectopic PGCs were found in the gonad mesenteries. These retain alkaline phosphatase staining (C, overlaid in D) and SSEA1 staining (E,F; green, GFP; red, anti-SSEA1 stain). In D, the arrow indicates alkaline phosphatase staining in blood vessels. In E and F, the plane of section is through the hilus of the gonad. The body of the gonad is out of focus (arrow in E). Scale bars: 145 µm in A; 163 µm in B-F.