[Degenerative changes in the central region of aging human rib cartilage, as influenced by growing cross section diameter (author's transl)].

In the centre of aged human rib cartilage, a yellowing degenerative zone is seen, while in a circular peripheral region the tissue remains unchanged. The cartilage of the 12th rib shows decrease in diameter towards its free end. It therefore was used as a model to find out wether there is a critical diameter of the diffusion stretch leading to a degeneration of the centre. This stretch was to be compared with the diameter of the peripheral circular zone. Cartilage of the second rib was used for comparison. The length of the free end showing no degeneration was 2,5- to 4 mm. Its radius was longer than the diameter of the circular zone in the middle part of the 12th rib cartilage, but this was not found in the second rib cartilage nor at the base of the 12th rib cartilage. The difference between the cartilage of differing individuals was more striking than the difference found between all cross sections of the second and 12th rib cartilage. The length of the diffusion stretch is thought to be an accessorial cause of aging besides the age changes of the cells and intercellular matrix, but not the only cause.