TISSUE SPECIFIC CHANGES IN DNA, RNA AND PROTEIN-CONTENT DURING LATE FETAL AND POSTNATAL-DEVELOPMENT IN THE RAT

1. 1. The levels of DNA, RNA, and protein in brain, heart, kidney, lung, liver and spleen have been studied in the rat during late fetal, peri- and postnatal development. 2. 2. The protein/DNA ratio increased with age in all tissues tested, supporting the view that the ratio of cytoplasm to nucleus increases with differentiation. 3. 3. A tissue specific pattern of the RNA/DNA ratio was observed with, however, highest and lowest values at quite different developmental stages. 4. 4. The possible relationships between the developmental changes in the macromolecular constituents and morphological, biochemical and functional changes in the various tissues have been discussed. © 1979.