Number of cells in body (see measurement section for methods)

Range [1] measuring the total amount of DNA 10^13 [2] counting number of cells in 1 g of tissue 3.5X10^13 cells/body
Organism Human Homo sapiens
Reference Renato Baserga, "The Biology of Cell Reproduction" 1985 Harvard University Press, p.52 bottom paragraph and p.53 top paragraph
Method "It is possible to calculate, approximately, the number of cells in an animal by [1] measuring the total amount of DNA. For instance, a mouse 25 grams in weight contains a total of 20 mg of DNA. Since diploid somatic cells (in mammals) have 6X10^-12 g of DNA, one can calculate that there are, in mouse, ~3X10^9 cells. By extrapolation, a 70 kg man should have in the order of 10^13 cells. A slightly different estimate [2] —3.5X10^13 cells—is obtained if one counts the number of cells in 1 g of tissues, which has roughly 5X10^8 cells. Incidentally, as one can see from table 4.1, the mass of a diploid liver cell in the rat is 2X10^-9 g, which again would give 5X10^8 cells. These figures are very approximate and should serve only as a guide."
Comments "It does not take a profound observer to realize that the most important mechanism in the growth of tissues is an increase in cell number, since all animals derive from a single fertilized egg cell. The adult rat liver alone has almost 2X10^9 cells, though the liver is much more cellular than the animal as a whole, which contains bones, tendons, cartilage, and other tissues that have a lot of intercellular substance and few nuclei."
Entered by Uri M
ID 110895