Fig. 5. Reduction in the number of PGCs reaching the genital ridge in CXCR4-mutant embryos. Cryosections of E10.5 (A,B), E11.5 (C,D) and E12.5 (E,F) control (+/+, A,C; +/-, E) and mutant (-/-, B,D,F) embryos. PGCs are stained with AP: black arrows indicate PGCs in the genital ridge and white arrows point to lost PGCs in mutant embryos. DA indicates position of dorsal aorta in each section. Scale bars: 0.5 mm. (G) Number of PGCs in control and mutant embryos. For each bar, PGCs were counted in eight transverse 20 µm sections distributed along the genital ridge. Error bars show standard deviation. There is a statistically significant difference in the number of PGCs between control and mutant embryos (Student's t-test, P<0.0001).