Abstract
Various types of polymeric materials were implanted subcutaneously in rats and the thickness of the fibrous tissue capsule formed around the implant was measured. Six tumors developed in 13 cases who survived for more than 18 months. Thickening of the capsule and suppression of metabolic activity in it may play an important role in the production of tumors. We assumed if the capsule thickness exceeds 0.2-0.25mm during 3-12 months tumor will occur after a certain latent period. Tumorigenesis by polymers in rats should be considered generally from the view point of aging and life span of the animal.
