Gene expression and immunolocalization of fibroblast growth factor 2 in the ovary and its effect on the in vitro culture of caprine preantral ovarian follicles.

This study quantified Fibroblast growth factor 2 (FGF-2) mRNA and localized FGF-2 protein in different categories of follicles isolated from goat ovaries. In addition, we verified the effects of this factor on the in vitro culture of preantral follicles isolated from goats. For mRNA quantification, we performed real-time PCR using primordial, primary and secondary follicles, as well as cumulus-oocyte complexes (COCs) and mural granulosa and theca cells of small and large antral follicles. For FGF-2 protein localization, the ovaries were subjected to conventional immunohistochemical procedures. Preantral follicles were isolated and cultured in vitro for 12 days in either control (basic) or supplemented with FGF-2 medium. The expression of FGF-2 mRNA was detected in all categories of follicles and there was no difference in preantral follicles and COCs or granulosa/theca cells from small and large antral follicles. However, in large antral follicles, COCs showed expression levels significantly lower than in granulosa/theca cells (p < 0.05). We observed moderate expression of FGF-2 protein in preantral follicles but not in granulosa cells of primordial follicles and theca cells of secondary follicles. In both small and large antral follicles, strong, moderate and weak staining was observed in oocytes, granulosa and theca cells, respectively. The addition of FGF-2 caused a significant increase in the daily follicular growth rate compared to the control group. We conclude that FGF-2 mRNA is expressed throughout follicular development and that its protein can be found in different patterns in preantral and antral follicles. Furthermore, FGF-2 increases the follicular growth rate in vitro.

Vascular endothelial growth factor-A(165) (VEGF-A(165)) stimulates the in vitro development and oocyte competence of goat preantral follicles.

The aim of this study was to evaluate the effect of vascular endothelial growth factor-A(165) (VEGF-A(165)) on the in vitro development of goat secondary preantral follicles. Preantral follicles (≥150 µm in diameter) were isolated from the ovaries of adult mixed-breed goats and individually cultured for 18 days in αMEM in the absence (control) or presence of VEGF-A(165) at concentrations of 10 ng/ml (VEGF10) and 100 ng/ml (VEGF100). Analyses of follicular survival, diameter, antrum formation and rate of daily growth were performed every 6 days. At the end of the culture period, morphologically normal oocytes (≥110 µm in diameter) were taken for in vitro maturation (IVM). The results demonstrated that all follicles presented oocytes and granulosa cells that were morphologically normal and after labeling with calcein-AM, high rates of oocyte viability were observed in all treatments. The follicular diameter and the growth rate achieved in the presence of VEGF10 were higher than those of the control. Both treatments with VEGF-A(165) showed higher rates of oocyte recovery for IVM when compared with the control. Moreover, only the addition of VEGF-A(165) permitted oocytes grown in vitro to reach metaphase II. Thus, the addition of VEGF-A(165) to the culture medium improves the development of goat preantral follicles cultured in vitro, allowing the production of mature oocytes.