Fibrogenesis.

A review of fibrogenesis by asbestos fibers is given. There is nothing to indicate that the fibrogenic effects of inhaled asbestos fibers should differ in any way from those of ingested asbestos. Recently, ingestion has assumed some importance concerning human exposure. Three sections dealing with the process of fibrogenesis are covered: the first deals with in vitro fibrogenesis, in particular the interrelation of macrophages damaged by dusts and the subsequent laying down of collagen by fibroblasts in culture; the second deals with in vivo fibrogenesis after the inoculation of extracts of silica-treated macrophages into various animals, and the third, with the fibrogenicity of a wide variety of mineral fibers in man and experimental animals. Recent studies described in the first section of the present review appear to offer a better understanding of the effects of macrophages on fibroblasts after tissue damage of various kinds has occurred.