Expression of Basic Fibroblast Growth Factor in the Rat Ovary: Detection of mRNA Using Reverse Transcription-Polymerase Chain Reaction Amplification

Abstract

Development of the ovarian follicle and corpus luteum involves proliferation and differentiation of several cell types: granulosa cells, thecal cells, and various stromal cells, particularly the endothelial cells that compose the rich thecal and luteal vascular networks. Basic fibroblast growth factor (bFGF) is a potent mitogen for cells of mesodermal and neuroectodermal origin, including endothelial cells. With the use of reverse transcription-polymerase chain reaction (PCR), we have examined the expression of bFGF in the rat ovary. RNA was extracted from fetal bovine aortic endothelial cells, hypothalami of adult rats, and either whole ovaries or isolated granulosa cells from PMSG-primed immature rats. The RNA was reverse transcribed and then amplified by PCR using two oligonucleotide primers specific for both bovine and rat bFGF. A sample of the PCR solution was size fractionated by electrophoresis in an 8% polyacrylamide gel, which was then stained with ethidium bromide and examined under ultraviolet light. When reverse transcription-PCR was performed on RNA from bovine endothelial cells, rat hypothalamus, or whole rat ovary, a single major DNA band corresponding in length to the distance between the 5'-ends of the two bFGF-specific primers (354 base pairs) was obtained. The identity of this material with the bovine and rat bFGF sequences was confirmed by restriction enzyme analysis. When RNA from isolated granulosa cells was examined, however, no bFGF mRNA was detected. These results confirm that the bFGF gene is expressed in the ovary during follicular development. Furthermore, they demonstrate that ovarian bFGF expression is cell specific, since granulosa cells do not contain detectable bFGF mRNA.