Vasoactive intestinal peptide improves the survival and development of caprine preantral follicles after in vitro tissue culture

Abstract

The aim of this study was to evaluate the effect of vasoactive intestinal peptide (VIP)on the survival, activation and growth of goat preantral follicles after in vitro culture. The ovarian cortex was divided into small pieces and one fragment was immediately fixed (control). The remaining fragments were cultured in vitro for 1 or 7 days at 39 degrees C and 5% CO(2), in supplemented minimum essential medium (MEM(+)) with or without different concentrations of VIP (1, 10, 50, 100 or 200 ng/ml). Noncultured (fresh control) and cultured ovarian fragments were processed for histological analysis and transmission electron microscopy. Follicles were classified as primordial or developing, and as normal or degenerated. Our findings indicate that when compared with control, addition of all concentrations of VIP except 200 ng/ml resulted in similar percentages of normal preantral follicles after 1 and 7 days of culture. Culture of ovarian cortex tissue for 1 and 7 days increased the percentage of follicular activation in all treatments when compared with control, except with 1 ng/ml of VIP after 1 day. However, no difference was observed between VIP-treated and MEM(+)-treated follicles. In addition, after 7 days of culture, the highest follicular and oocyte diameters were observed in follicles cultured with 10 ng/ml VIP relative to MEM(+) alone. Transmission electron microscopy showed ultrastructural integrity of follicles after 7 days of culture in 10 ng/ml VIP. In conclusion, this study demonstrates that VIP maintains follicular integrity and stimulates caprine preantral follicle growth.