Ultrastructural effects of riboflavin deficiency on rat hepatic mitochondria

Abstract The hepatic mitochondria of rats fed a riboflavin‐deficient diet were examined by electron microscopy. Discoidal mitochondria with elongated cristae increased in frequency from day 4 to day 12 of the test diet. At day 22, sheaves of closely packed cristae were present in many otherwise typical mitochondria. At day 53, numerous cupshaped mitochondria appeared; these often nested one inside the other. From this day onward, the mitochondria showed a tendency towards increasing size. By day 82, some had a diameter greater than 8 μm. These and other, smaller mitochondria often contained extremely prominent matrix granules. The production by riboflavin‐deficiency of giant mitochondria in the rat liver appears to be unrelated to their capacity to carry out oxidative metabolism.