The purposes of this experiment were to: (1) test if fibroblast growth factor (FGF) induced elongation of cultured rat lens epithelial cells (LEC) and (2) determine if selenite affected elongation of LEC. FGF (125-500 ng/ml) reduced the number of colonies of LEC, but it did not induce elongation when cells were cultured on plastic dishes. One hundred micromolar and, to a lesser extent, 10 mumol/l selenite also reduced the number of colonies of LEC. Coculture of FGF and selenite on plastic caused a synergistic reduction in the number of colonies. FGF (125-1000 ng/ml) induced a dramatic morphologic change in LEC. Elongated processes radiated from stellate-like cell aggregates when cells were cultured on reconstituted basement membrane matrix (Matrigel). Again, 100 mumol/l selenite and, to a lesser extent, 10 mumol/l selenite reduced the number of cell aggregates with processes on Matrigel. These results indicated that an inhibitory effect of selenite on the elongation of LEC may be a factor in the development of selenite cortical cataract.