Cell proliferation assay showing the BrdU-labelled cells in the developing heart of embryos from control (A, B) and diabetic (C, D) mice. BrdU-labelled cells appear to be decreased in the EC (asterisk) and the ventricular myocardium (arrow) in the defective heart of experimental embryos (C, D) when compared to controls (A, B). Quantitative analysis demonstrates that the proliferation index (E) is significantly decreased in the embryonic hearts of diabetic mice (filled bar). Bar A, B, C, D 50 μm. Mean values ± SD (n = 3). *: P < 0.05.