Embryos (E13.5) obtained from control (A-C) and diabetic (D-F) mice. Embryo from control mice shows no gross abnormalities (A). In control embryos, the Ao and PT have separated (arrows) and are connected to the LV and RV respectively (connections verified by sectioning, data not shown) (B). In addition, the myocardium and trabeculae are well developed (C). High magnification of the superior aspect of the VS (C'). Embryo from diabetic mice shows neural tube defect (arrow) (D). In addition, there is a single outflow vessel (arrow), which is wholly committed to the RV (E). Further, the secondary ventricular foramen has failed to closed, histological derangements constituting the myocardium and trabeculae are observed, and the epicardium is disorganized (F). High magnification of the ventricular foramen (F'). Bar C, F 500 μm; C', F' 50 μm.