[Age and features of DNA replication in intact white rat liver].

Studies on 3H-thymidine incorporation into DNA of 6- and 24-month-old rat liver have shown that part of newly formed DNA of both adult and old species is extracted as single-stranded after hydroxyapatite chromatography. This single-stranded DNA seems likely to be an intermediate product of DNA replication. The transition of the newly formed single-stranded DNA to double stranded proceeds more slowly in the liver of old animals than in adult ones.