Recent studies indicate that reproductive hormones may stimulate target cell growth via the actions of growth factors. In this study, reverse transcription-polymerase chain reaction analysis was used to assess the effects of in vivo diethylstilbestrol (DES) treatment on granulosa cell (GC) and thecal-interstitial cell (TIC) transforming growth factor (TGF)-beta 2 mRNA expression. In response to DES, GC expression of TGF-beta 2 mRNA was stimulated approximately 6.8-fold. By contrast, DES did not significantly alter TIC expression of TGF-beta 2 mRNA. Data were normalized relative to glyceraldehyde-3-phosphate dehydrogenase mRNA levels, which were unaffected by DES. These results extend our earlier findings, which demonstrated that GC and TIC expression of TGF-beta 2 mRNA is regulated by gonadotropins in vitro, to include steroidal regulation in vivo of intraovarian growth factor expression. Collectively, the present study and previous results support the following concepts: 1) intraovarian TGF-beta 2 mRNA expression is regulated by both gonadotropins and steroids, and 2) GC and TIC expression of TGF-beta 2 mRNA are differentially regulated.