[Electron microscopic studies of pseudointima in synthetic prostheses].

Thirty one prostheses made of Lavsan (therylene) or teflon-lavsan that had been functioning in human patients for 16 months to 21 years were examined. No continuous endothelial lining was found present on the pseudointimal surface of any of the prostheses. The major cell types in a formed, well-vascularized pseudointima were fibroblasts and smooth-muscle cells. Cells of the macrophage series were involved in forming the granulation tissue seen around fibers of the prostheses.