Tumor necrosis factor-alpha (TNF-alpha) messenger RNA (mRNA) in rat ovaries was detected by Northern blot analysis and by reverse transcription-polymerase chain reaction (RT-PCR). Northern blot analysis of total cellular RNA (tcRNA) isolated from adult rat ovaries showed a single distinct band at approximately 2 kilobases, while rat white blood cells, used as control, also showed a second lower band at approximately 0.5 kilobases. TNF-alpha expression in ovaries was also detected by RT-PCR, using RNA-specific primers. Southern blot analysis of the RT-PCR products showed a single band of the expected 500 base pairs, from the ovary and white blood cells, using either tcRNA or polyA+ RNA. In order to validate the RT-PCR product, it was digested with restriction enzymes, HhaI, HindIII, and XhoI. The results indicate that the ovarian TNF-alpha mRNA does not contain major alterations with respect to the known structure of rat TNF-alpha mRNA. Ovarian RNA was also subjected to PCR without previous RT in order to amplify, if any, contaminating genomic DNA. A single band of approximately 900 base pairs was observed, which contained introns 1 and 2 (determined by restriction enzyme digestion). In summary, these results indicate that rat ovaries contain TNF-alpha mRNA which makes it a likely source of local TNF-alpha secretion. The possibility exists that ovarian cells and/or macrophages are the source of the ovarian TNF-alpha mRNA.