CONTACT INHIBITION, MACROMOLECULAR SYNTHESIS, AND POLYRIBOSOMES IN CULTURED HUMAN DIPLOID FIBROBLASTS

Abstract

In cultures of human diploid fibroblasts, the rates of DNA, RNA, and protein synthesis per cell are progressively depressed as the culture becomes confluent, reaching levels 5-15% of those in the freshly inoculated culture in the case of DNA and RNA, and 30-50% in the case of protein. These decreases are associated with the disappearance of most of the free cytoplasmic polyribosomes. The changes are completely and rapidly reversible on subdivision of the culture.