||"If one considers that protein comprises roughly 20% of body
mass (Brozek, J., Grande, F., Anderson, J. T., and Keys, A. (1963) Ann. N. Y. Acad.
of Sci. 110, 113–140) and that 30% or more of total protein is represented by
collagen (Lehninger, A. L. (1975) Biochemistry, 2nd Ed., p. 135, Worth Publishers, Inc.,
New York AND Hall, D. A. (ed) (1964) International Review of Connective Tissue Research, Vol.
2, p. 244, Academic Press, New York), and if it is assumed that type I collagen
comprises at least 90% of total collagen, it can be calculated
that an adult of 70 kg may contain more than 1?10^21 type I