Peritoneal fibrosis due to practolol. Scanning electron microscopical and histological observations.

Three cases of peritoneal fibrosis induced by the beta adrenoceptor blocking agent practolol are presented. Histological and scanning electron microscopical specimens showed a thick layer of loose connective tissue with collagen bundles and fibroblasts. No evidence of mesothelial cells with characteristic microvilli was found. The conclusion is drawn that the basic feature of practolol peritonitis is the destruction of the mesothelial membrane and a slowly progressive formation of loose connective tissue. The reason for the increased formation of connective tissue and the cause of the excessive activity of fibroblasts are discussed.