An Electron Microscopic Study on the Morphological Changes of Isolated Rat Liver Mitochondria by Aging

Abstract

The morphological changes of the mitochondria in the course of aging were examined by electron microscope and by the measurement of absorbance at 520 mμ. 1. Freshly prepared mit ochondria in 0.25 M sucrose (pH 7.4)were swollen. The cristae had a vesicular outline. 2. Mitochondria aged 5 days showed more swollen. The membranes pulled away from the cristae which became concentrated in one mass: At one extreme of structural variation, mitochondria appeared grossly distended with a very few irregular cristae and often with ruptured membranes. 3. Mitochondria aged 10 days showed as small particles. Many of them contained cristae, but some had no such structures, and showed as small and round vacuoles which were randomly arranged. There were also rests of membranes and cristae which might be produced from broken mitochondria. The same tendency and similar results were observed also in the mitochondria aged 15 days. 4. Mitochondria aged 20 days showed also as small particles, some of which seemed to become slightly larger than the mitochondria aged 15 days. 5. The absorbance changes of the aged mitochondria showed the identical results as above described findings about the changes of the size in the course of aging. Absorbance rapidly decreased to 5 days, then increased slightly to 15 days, and finally gradually decreased.