Insulin-like growth factor II (IGF-II) and follicle stimulating hormone (FSH) combinations can improve the in vitro development of grown oocytes enclosed in caprine preantral follicles

摘要

Objective: Evaluate the possible role of IGF-II alone or in association with FSH on in vitro development of isolated caprine preantral follicles. Methods: Preantral follicles (?? 150??m) were isolated from goat ovaries and cultured for 18. days in basic ??MEM medium (control) or supplemented with IGF-II alone at 20 or 50. ng/ml, named IGF20 and IGF50, respectively, or in combination with recombinant FSH (FSH, IGF20F or IGF50F). During in vitro culture, the follicles were analyzed by using morphology criteria, antrum formation and growth rate as parameters. After 18. days of follicular culture, oocytes equal to or larger than 110??m were used for in vitro maturation (IVM). Oocyte viability and meiosis resumption were assessed by fluorescence microscopy after labeling with calcein-AM, ethidium homodimer and Hoechst 33342. Results: The IGF20 treatment was the only treatment capable of maintaining the percentage of morphologically normal follicles from D0 until D6 and from D12 to D18 (p > 0.05), while in all other treatments the percentage of morphologically normal follicles decreased progressively during 18. days of in vitro culture (p < 0.05). At D18, all treatments with IGF-II or FSH resulted in a significantly higher percentage of normal follicles when compared to ??MEM alone. The IGF50F treatment provided a significantly higher early antrum formation rate when compared to ??MEM and FSH alone. The addition of IGF-II alone (20 or 50. ng/ml) or in combination with FSH prevented oocyte degeneration after IVM. Moreover, the FSH treatment demonstrated a lower percentage of oocyte degeneration when compared to control (4.35% vs. 26.3%, respectively; p < 0.05). Regarding meiosis resumption, the IGF20F treatment was the only treatment that significantly differed from ??MEM alone. All treatments except the control (??MEM alone) presented oocytes at metaphase II. Conclusion: IGF-II associated with FSH stimulated in vitro follicular development, oocyte viability and meiotic resumption of caprine oocytes after IVM. ? 2013 Elsevier Ltd.