TUNEL assay shows the apoptotic cells in the embryonic heart of control (A, B) and diabetic (C, D) mice. Apoptotic cells appear to be increased in the EC (asterisk) and ventricular myocardium (arrow) in embryos of diabetic mice (c, d) as compared with those of controls (A, B). Inset shows high magnification of the apoptotic cells in the ventricular myocardium (B, D). Quantitative analysis shows that the apoptotic cells (E) are significantly increased in the developing heart of diabetic mice (filled bar). Bar A, B, C, D 50 μm. Mean values ± SD (n = 3). **: P < 0.001.