MORPHOMETRIC STUDY OF DENSITY OF MITOCHONDRIAL CRISTAE IN HEART AND LIVER OF AGING MICE

Mitochondria in sections of left ventricular wall and liver from C57BL/6J mice, 9, 18 and 36 mo. old, were analyzed using stereological procedures. At 9 mo. of age .mu.2 cristae surface per .mu.3 cytoplasm (Sv-c/c) was 5-fold greater in heart compared with liver reflecting the larger values in the former for both .mu.2 cristae surface per .mu.3 mitochondrion (Sv-c/m) and .mu.3 mitochondria per .mu.3 cytoplasm (Vv-m): Sv-c/c = Sv-c/m .cntdot. Vv-m. At 36 mo. in both tissues, Sv-c/c had decreased to 65% of the earlier value. This was due to a decrease in Vv-m alone in heart and both Vv-m and Sv-c/m in liver. In both tissues the number of mitochondria per .mu.3 cytoplasm (Nv-m) also decreased with age, while .mu.3 organelle average volume (vm) remained constant, supporting previous observations: Vv-m = Nv-m .cntdot. vm. Different tissues in the same organism age independently; mitochondrial inner and outer membranes have a semi-independent existence.