Abstract
Summary
Nitrogen and phosphorus contents of large and small granules and cytoplasmic supernatant from livers of mice 1 1/2-2, 6-7, 10-11, and 18-21 months of age were determined and expressed on a per nucleus basis. There were increased nitrogen contents, and relatively smaller increases in phosphorus contents in each of these fractions in older animals. The results, viewed in the light of observations of Weinbach and Garbus (7), suggest that as an animal ages, its liver cells lose metabolic capacity, and, also, that an attempt is made to restore at least some aspects of it by forming more of the active sites within the cell. Cell fractions examined in older animals differed chemically from those in younger animals, however, as indicated by decreased P/N ratios.
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