Freshly harvested granulosa cells (GC) from diethylstilbestrol (DES)-treated rats were examined for the presence of transforming growth factor-beta 1 (TGF-beta 1) and TGF-beta 2 mRNA by Northern analysis. TGF-beta 1 mRNA was not detectable, but hybridization of total RNA with a radiolabeled TGF-beta 2 cDNA probe revealed two mRNA species (5.1 and 3.6 kb) indicative of TGF-beta 2 mRNA. In response to FSH (50 ng/ml), relative TGF-beta 2 mRNA concentrations in cultured GC were 54% of control levels. Furthermore, the conditioned culture medium from FSH-treated GC contained significantly lower (p less than 0.01) TGF-beta-like activity relative to controls. These results demonstrate that rat GC express TGF-beta 2 mRNA which is regulatable by FSH in vitro.