Age-related changes in hepatic fine structure: a quantitative analysis.

Age-related changes in hepatic fine structure were quantitatively evaluated in virgin and retired breeder (RB) male rats by morphometric analysis. Centrolobular hepatocytes increase in size, at least up to 480 days of age, and this increase is reflected in larger volumes of nuclei, cytoplasm, organelles, and ground substance. The surface area of the smooth-surfaced endoplasmic reticulum (SER) continues to increase with age in both groups of animals, although there is a significantly greater amount of both SER and rough-surfaced endoplasmic reticulum in the livers of the virgin rats. In addition, aging is accompanied by a gradual increase in the relative volume of the lysosomes and a linear decrease in the surface area of the Golgi membranes. Evidence from this study suggests that specific alterations in hepatic fine structure occur as a function of age.