The Significance of DNA Methylation in Cellular Aging
Primary cultures of diploid fibroblasts give rise to populations which have limited growth potential. In the case of human cells, their in vitro life span is usually in the range of 50–70 population doublings (Hayflick, 1965; 1977; Holliday et al., 1977). In spite of strong selective pressure when growth slows down and finally ceases, permanent lines do not emerge from these populations. Diploid rodent cultures have a much shorter in vitro life span, and permanent lines, exemplified by the mouse 3T3 strain, often take over the culture (Todaro and Green, 1963).
KeywordsCellular Aging Diploid Cell Population Doubling Level Serial Subculture Somatic Mutation Theory
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