Number of cells

Range newborn ~3E+9: old age ~6E+10 cells/body
Organism Rat Rattus norvegicus
Reference Cairns J. 1975. Mutation selection and the natural history of cancer. Nature 255: 197–200. p.197 left column 2nd paragraphPubMed ID1143315
Comments "The cells of the surface epithelia that separate a typical mammal from its environment undergo continual turnover, and this turnover accounts for most of the cell division that occurs in the life of the animal. For example, a newborn rat contains some 3X10^9 cells and grows to a final value of about 6X10^10 cells in old age. Excluding any programmed cell death, the rat therefore represents a total of 6X10^10 cell divisions."
Entered by Uri M
ID 110649