Fig. 3. Sustained FGF expression increases the number of proliferating OEPD cells. (A) Control embryos showing phosphohistone H3 localisation. The boxed region demarcates the approximate area of the OEPD and cells were counted in this region. (B) Unilaterally pEF-Fgf electroporated embryos transfected on the right side, showing phospho-histone H3 (PHH3) localisation. The number of PHH3-positive cells in the OEPD were counted and compared between the left, unelectroporated,side and the right, electroporated side. (C) Graph showing the difference in the number of PHH3-positive OEPD cells between left and right sides of control and pEF-Fgf electroporated embryos. In control, non-electroporated embryos, the right side of the embryo has 3% fewer PHH3-positive cells (n=565 in 10 embryos) than the left (n=575 in 10 embryos). The right side of experimental embryos, electroporated with pEF-Fgf3 and pEF-Fgf19, has 24% more PHH3-positive cells (n=347 in six embryos) than the left, non-electroporated side (n=261 in six embryos). P-value is <0.001.