Epicardial proliferation is regulated by Hh signalling. a, Freshly dissected tcf21: nuceGFP hearts were randomly separated into two groups and cultured for 47 h with vehicle (n = 11) or 5 uM Cyclopamine (n = 8). Then, 25 uM EdU was added to the medium for 1 h before collection at 48 h. Cyclopamine treatment decreases epicardial cell proliferation ex vivo. Arrows indicate representative eGFP+ (green) EdU+ (red) nuclei. b, Quantification of eGFP+EdU+ nuclei on the ventricular surface, from hearts in a. **P < 0.01, Student's two-tailed t-test. c, tcf21: nuceGFP adult fish were subjected to partial ventricular resection surgery, and randomly separated into two groups for treatment with vehicle (n = 8) or 10 uM Cyclopamine (n = 10) from 2 to 3 dpa. Then, 10 mM EdU was injected intraperitoneally 1 h before collection. Cyclopamine treatment decreases epicardial cell proliferation in vivo. Arrowheads indicate representative eGFP+ (green) EdU+ (red) nuclei. d, Quantification of eGFP+EdU+ nuclei on the ventricular surface, from hearts in c. ***P < 0.001; Mann-Whitney rank sum test. c, Yellow dashed lines indicate resection plane; white dashed lines delineate ventricle. a, c, Boxed areas, magnified views. Scale bars, 50 um. Error bars indicate s.d.
