Electron microscopic radioautographic studies on DNA synthesis in the hepatocytes of aging mice as observed by image...

Quantitative changes of DNA synthesis in the hepatocytes of aging mice were studied by electron microscopic radioautography. Ultrastructural changes of labelled and unlabelled hepatocytes were estimated quantitatively by the image analysis. The results revealed that at various ages, the area of the cytoplasm and nuclei of labelled hepatocytes were more than those of the unlabelled cells. No significant changes were observed in the nucleoli. The area of the endoplasmic reticulum and mitochondria were less in the labelled hepatocytes than in the unlabelled hepatocytes. The number of the mitochondria was less in the labelled hepatocytes than in the unlabelled hepatocytes. The cell organelles of the hepatocytes that were synthesizing DNA were not well developed, as compared to those not synthesizing DNA during the postnatal development.