[Possible causes of change in collagen metabolism in aging].

At the beginning the different collagen types and their occurrence will be illustrated. The present known collagen changes - due to age alterations - will then be demonstrated and explained with examples: 1. Elasticity decrease of the collagen fibre due to stronging of the cross-links 2. Decrease of turnover 3. Increase of hydroxyproline and hydrolysine ; decrease of proline and lysine 4. Increase of the non-enzymatic glycosylation. The following comes into question as possible cause for age-changes to such degrees: decrease of water portion, decrease and change of the glycosaminoglycan-types, radical-formation, decrease of cell numbers and activity, immunity defect and general age changes.