Mitochondrial ultrastructure is disordered, and dense core insulin granule number is decreased in pancreatic β-cells from
5- and 10-week-old MKR islets. Electron micrographs are shown of ultra-thin sections of islets. β-Cells from 3-week-old WT
mice (A) and MKR mice (B) had normal mitochondria (C). Mitochondria in β-cells of 5-week-old MKR mice (E) were slightly swollen (F). The mitochondria of β-cells from 10-week-old MKR diabetic mice (H) were reduced in number and severely swollen with disordered cristae (I) compared with normal mitochondrial morphology in WT control (G). 30,000× magnification. Scale bar equals 500 nm and is shown in the bottom right in H. White arrows indicate mitochondria. Arrowheads indicate insulin granules. Quantitation of total number of mitochondria and
average mitochondrial area in 3-week-old (C), 5-week-old (F), and 10-week-old (I) WT and MKR electron microscopic sections. Dense core insulin granules were counted in images at 10,000× magnification (Fig.
S6) and number was quantified (J). A total of 50–100 images were analyzed per age with 5–7 mice per genotype. Data are means ± SE. *P < 0.05; **P < 0.01; ***P < 0.001 compared with age-matched WT.