Age changes in collagen characteristics of bone and skin of a short-lived species of reptile.

Decalcified bone collagen of older male garden lizards, Calotes versicolor, was less susceptible to digestion by collagenase from Clostridium histolyticum than that from younger individuals. In aged skin the percentage solubility and the soluble/insoluble collagen ratio decreased, with a concomitant rise in insoluble and total collagen. Collagen/unit area increased with advancing age in both dorsal and ventral skin. These results from a non-mammalian poikilothermic vertebrate provide additional evidence in favour of the cross-linkage theory of ageing and suggest a common pattern of collagen ageing in vertebrates.