Figure EV4. TEM of myocardium and ultrastructural features of mitochondria in Tfam mKO on Dele1+/− and Dele1 KO backgrounds.

(A–C) Representative TEM images acquired at 2000× direct magnification show areas of myocardium of indicated genotype used for analysis of mitochondria. Yellow star in (B) indicates a myocyte with milder structural phenotype compared to neighboring myocytes, illustrating the observed mosaicism of the phenotype. Scale bar = 5 µm. (D) Image of the subarea boxed yellow in (B), acquired at 5000× direct magnification and representative of images used to quantify ultrastructural features of mitochondria detailed in Fig. 3. Scale bar = 2.5 µm. (E) Tfam mKO mitochondria displayed populations of closely aligned “stacked” cristae (black arrows) and sparse areas filled with a granular matrix material and few cristae (open white arrowheads). Scale bar = 500 nm. The mitochondrion in the bottom left image is cropped from same cell as the mitochondrion shown in (Fig. 3F, middle). At least some Images of mitochondria are taken from the same cell. (F) Examples of crumpled cristae (white arrows) that occurred in Tfam mKO mitochondria. Scale bar = 500 nm. At least some Images of mitochondria are taken from the same cell. (G) This panel shows enlargements of images that are also shown in (Fig. EV4E, boxed area with “stacked cristae”) and (Fig. EV4F, boxed area with “crumpled cristae”). Scale bar = 250 nm. Source data are available online for this figure.