Differential gene expression of fibroblast growth factor receptor isoforms in rat ovary

The gene expression of four fibroblast growth factor receptors (flg, bek, FGFR-3, and FGFR-4) in rat ovary cells was studied. Northern blot hybridization revealed that flg and bek mRNAs were detectable during all stages except a diestrus stage, whereas FGFR-3 and FGFR-4 mRNAs were almost undetectable throughout the cycles. In situ hybridization also demonstrated that only flg and bek gene expression was detectable. A modest flg mRNA signal was detected in developing antral follicles and it was more prominent in the theca-interstitial cells than in the granulosa cells. A modest to weak flg mRNA signal was seen in the hypertrophied theca-interstitial cells of atretic follicles and a very weak flg mRNA signal was observed in the corpora lutea. On the other hand, a weak bek mRNA signal was seen in granulosa and theca-interstitial cells in developing follicles and also hypertrophied theca-interstitial cells of atretic follicles, but not in the corpora lutea. Intense signals for both flg and bek mRNAs were unexpectedly found in the epithelium of paroophoron at the hilus. These results demonstrate that the bFGF receptor isoforms are expressed differentially in the rat ovary cells.