Study of the effects of aging on macromolecular synthesis in various organ systems using microscopic radioautography

In order to elucidate the effects of aging on macromolecular synthesis such as DNA, RNA, proteins, glucides and lipids in various organ systems of experimental animals and humans, systematic studies using light and electron microscopic radioautography in various organ systems including skeletal, muscular, digestive, respiratory, urinary, reproductive, endocrine, circulatory, nervous and sensory systems were studied after incorporation with macromolecular precursors. The experimental animals used were mainly ddY strain mice from embryo to postnatal days 1 and 3, weeks 1 and 2 or months 1, 2 and 6 months up to 1 and 2 years senescent stages. Animals were injected with [3H]-thymidine for DNA, [3H]-uridine for RNA, [3H]-amino acids for proteins, [3H]-glucose, [3H]-glucosamine and [35S]O4 for glucides, [3H]-glycerol for lipids and some low molecular target tracers such as hormones, inorganic substances and drugs. Results demonstrate that these precursors when incorporated into various cell types in various organs showed specific patterns of macromolecular synthesis as observed in perinatal to juvenile, mature and senescent stages. These effects of aging could answer some of the questions as to how but not why we get old.