Ovarian germinal epithelial cells respond to basic fibroblast growth factor and express its gene: implications for early folliculogenesis.

Cultured bovine ovarian germinal epithelial (OGE) cells respond to fibroblast growth factor (FGF) with an increased rate of proliferation. The basic form of FGF (bFGF) had an ED50 of 110 pg/ml, while the acidic form had an ED50 of 3.5 ng/ml. The mitogenic effect of FGF was blocked by transforming growth factor-beta. OGE cells express the gene encoding bFGF. The bFGF gene is transcribed into 7.0- and 3.7-kilobase mRNA transcripts, which are translated into 18,600 mol wt bFGF-like growth factor. OGE-derived bFGF is bioactive and stimulates the proliferation of capillary endothelial cells or OGE cells. This mitogenic effect is prevented by specific neutralizing anti-bFGF antibodies. Our results indicate that bFGF derived from OGE cells can act as both autocrine and paracrine growth factor for that cell type, and they further suggest that the factor may be involved in the development of early follicles.