Studies on basic fibroblast growth factor (FGF-beta) gene expression in the rat and pig ovary using in situ hybridization and quantitative reverse transcriptase--polymerase chain reaction techniques.

In order to gain further understanding of the physiology of basic fibroblast growth factor (FGF-beta) in the mammalian reproductive tract, the expression of FGF-beta mRNA in the rat and porcine ovary has been examined by in situ hybridization and quantitative reverse transcriptase-polymerase chain reaction techniques during different stages of the estrus cycle. The results confirm that an increase in FGF-beta mRNA levels occurs over the course of the estrus cycle. No FGF-beta gene expression was detected during diestrus, the non-hormonal phase of the cycle, or at the early proestrus stage of the cycle. During late proestrus and estrus, FGF-beta mRNA was predominantly localized to granulosa cells of the dominant follicles, and to a lesser extent, to secondary antral follicles not committed to ovulation. These cells also expressed FGF-beta mRNA during this phase of follicular development, albeit in low abundance. During metestrus, after ovulation, in the newly formed corpora lutea FGF-beta mRNA levels were maximal, however on entering the next cycle commencing at diestrus, no FGF-beta mRNA was observed in the degenerating corpora lutea. These results indicate that expression of the FGF-beta gene is differentially regulated during the estrus cycle. The biological significance of this expression and the potential role of FGF-beta in local intra-ovarian regulation of the repetitive cycles of follicular differentiation, proliferation and maturation associated with ovarian revascularization are discussed.