| Abstract: | Measurement of area, circumference and total length of membrane profile of mitochondria of hepatic cells in 61 human biopsy materials (age range 21 to 81 years) have been ultramicrometrically performed on electron micrographs, supplemented by electroncytochemical examination of cytochrome c oxidase activity in some cases. The mitochondria decreased in number after 60 years of age. The first stage of compensation for the numerical loss of mitochondria was achieved by an increase of cristae in each mitochondrion, followed with a five year lag by an increase in their size. Formation of enlarged and giant mitochondria in aging process following the significant decrease in their number, may be considered to be of similar mechanism to polyploidization of the nucleus, whose division is interfered. |
