Ovarian transforming growth factor-alpha gene expression: immunohistochemical localization to the theca-interstitial cells.

Rat ovaries were examined for the presence of transforming growth factor-alpha (TGF-alpha). Immature diethylstilbestrol-primed rats were treated for 3 days prior to sacrifice with or without FSH. Their ovaries were either fixed in formaldehyde for immunohistochemistry or the RNA was extracted for northern blot analysis. Hybridization with a rat TGF-alpha cDNA probe revealed a 4.5 kilobase mRNA whose abundance was markedly stimulated in the rats treated with FSH. Immunohistochemical staining, using a sequence specific monoclonal antibody to TGF-alpha, MF9, detected immunoreactive TGF-alpha only in the interstitial and theca cells. FSH treatment resulted in no appreciable change in the immunostaining. These results suggest that TGF-alpha is synthesized in the ovary, perhaps in the theca-interstitial compartment.