Fig. 7. Alterations of cardiomyocytes in CAR-deficient embryos. Ultrathin sections of the heart of E11.5 CAR^+/+ (left) and CAR^-/- (right) littermate embryos (A-D) were analyzed by transmission electron microscopy. The micrographs show alterations within cardiomyocytes, such as enlarged mitochondria (M), mitochondria with increased electron density (^*). Most importantly large areas of the cytosol of CAR^-/- cardiomyocytes were devoid of myofilament bundles and the thickness of these bundles was much reduced (arrows). Bar in A and B represents 0.5 µm, and in C and D 1 µm. (E,F) Semi-thin sections of E11.5 embryos of both genotypes were prepared and the heart region was stained for the accumulation of glycogen granula by periodic acid Schiff staining. Note that CAR^-/- embryos showed a strong increase in glycogen storage. Bar, 25 µm.