Ultrastructural changes in lung fibroblast cultures exposed to chrysotile asbestos.

Early changes in the ultrastructure of lung fibroblasts exposed to chrysotile asbestos are described. The dust exposed cells rapidly undergo a “maturation process” reflected by highly dilated endoplasmic cisternae, irregularity in nuclear outline and composition and the appearance of membrane microvilli which are all characteristics of normal cells in the stationary phase. It is suggested the surviving cells undergoing this “maturation process” may account in part for the higher synthetic activity, leading to increased collagen levels, in chrysotile exposed cultures.