Mechanical properties of the collagenous framework of skin in rats of different ages

Abstract

The collagen content, tensile strength, and extensibility of the skin of rats have been examined in rats 3–85 weeks of age. Tensile strength calculated per unit cross-sectional area of collagen increased with age, the maximal value in the oldest group (5.5 kg/mm2 collagen) being about three times that in the youngest. The quantity present per unit area of surface also increased with age. An estimate of the total "surface mechanical resistance" obtained by multiplying collagen per unit area of skin and tensile strength rose continuously about twentyfold between the youngest to oldest of the groups. Application of a load produces after a time an elongation at constant rate ( K). Extensibility, measured by the ratio of this rate to length at zero time ( l0) obtained by extrapolation, and corrected to constant load of 100 g/mm2 cross-sectional area of collagen, was found to fall with age, the range being about eightyfold.