[Wound healing in old age (experimental studies on rats) (author's transl)].

Autoradiographic studies on wound healing after experimental myocardial infarction in rats aged 6 weeks, 5 and 21 months gave the following results: 1. The interval between damage, DNA-replication and mitotic activity of the cells is age-dependent. 2. Age does not influence the capacity of the connective-tissue cells to synthesize tropocollagen. However, the number of synthesizing fibroblasts is reduced. 3. The collagen changes occuring during wound healing are not of primary, but of secondary nature; they take place if the mucopolysaccharide content is reduced. As a result, there is a decrease in the ground-substance synthesis in ageing granulation tissue. In cicatricial tissue the content of amorphous ground-substance remains greatly constant. 4. Consequently, the ageing of the collagen is governed by a biologically regulated process whose control mechanism is inherent in the cells.