Fig. 3

Nkx genes regulate OFT progenitor proliferation timing and differentiation. (A-D) Ventral view of the arterial pole region at 40 hpf. Confocal projections of immunohistochemistry for EdU (red), ZsYellow (green) and MF20 (gray) in embryos carrying Tg(nkx2.5:ZsYellow) following EdU incubation at 18 hpf in wild-type (A,B) and nkx2.5^−/−;nkx2.7^+/+ (C,D) embryos. White arrows indicate EdU⁺ ZsYellow⁺ cells. The boxed areas in A,C are shown at higher magnification in B,D. (E-G) Proliferation indices showing a statistically significant increase in undifferentiated, ZsYellow⁺ MF20⁻ progenitors in nkx mutant (n=6) compared with wild-type (n=6) embryos (G); the proliferation index is comparable in the proximal, ZsYellow⁺ MF20⁺ CM population contributing to the arterial pole (F) as well as in the total OFT, ZsYellow⁺ MF20^+/− CM population (E). Student's t-test was used to determine statistical significance. The mean and s.e.m. of each data set are shown (*P<0.005).