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

¹ Department of Physiology, University College London, London, England

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.

Key Words: skin extensibility in aging • skin collagen content • collagen tensile strength and extensibility • aging and skin composition

Submitted on August 20, 1963