Immunohistochemical detection of insulin-like growth factor-I, transforming growth factor-beta2, basic fibroblast growth factor and epidermal growth factor-receptor expression in developing rat ovary

The aim of this study was to determine the immunohistochemical expression and localization of insulin-like growth factor-I (IGF-I), transforming growth factor-beta2 (TGF-beta2), basic fibroblast growth factor (bFGF) and epidermal growth factor-receptor (EGF-R) in developing rat ovaries. Eighteen female Wistar rats were enrolled in this study; newborn (n=6), one-month-old (n=6) and adult (n=6) rats. Formalin-fixed and parafin-embedded ovarian tissues were stained with antibodies against IGF-I, TGF-beta2, bFGF and EGF-R, immunohistochemically. The ovarian cells were evaluated by semi-quantitative scoring system under light microscope. The staining of IGF-I, TGF-beta2, bFGF and EGF-R were most intense in the oocytes and were heavily at one-month-old rats. A moderate immunostaining in theca cells and corpus luteii reacted with IGF-I in adult rats. Furthermore the staining intensity for IGF-I was moderate in granulosa cells of newborn rat ovaries. We detected also a moderate staining for TGF-beta2 in corpus luteii of adult rats. In addition, we found a bFGF immunostaining mainly in oocytes of follicles of young and adult rats. Immunostaining for EGF-R was moderate in granulosa cells of one-month-old rats. In conclusion, this study suggests that growth factors play a pivotal role in ovarian function, especially in follicular development. The role of growth factor in controlling degeneration or growth (or both) of ovary follicles remain as explained.