In vitro maturation of pig oocytes with different media, hormone and meiosis inhibitors

This study evaluated in vitro maturation (IVM) of pig oocytes in two maturation media (TCM199 and NCSU23) supplemented with 10% porcine follicular fluid (pFF) or 0.1% polyvinyl alcohol (PVA) and four hormonal treatments. The best media was then used to evaluate the effect of reversible meiosis inhibitors cycloheximide (CHX) (5 μM) and butyrolactone I (12.5 μM) on the maturation of pig oocytes was evaluated. After maturation for 44 h, the oocytes were fixed, stained and examined under epifluorescence microscopy. The comparison of the proportion of oocytes in metaphase II (MII) revealed that hormonal Treatment 2 (incubation for 22 h–10 ng EGF/ml, 10 IU hCG/ml and 10 IU eCG/ml, followed by incubation for 22 h–10 ng EGF/ml) presented higher repeatability percentages: TCM + PVA (54.5%, 61/112); TCM + pFF (65.0%, 63/97); NCSU23 + PVA (54.6%, 65/119) and NCSU23 + pFF (58.1%, 61/105). The comparison of maturation media showed that TCM199 presented more constant results than NCSU23. Regarding supplementation with pFF or PVA, TCM199 with pFF presented better results. The comparison between butyrolactone I and cycloheximide demonstrated that both drugs effectively inhibited meiosis; however, only cycloheximide presented metaphase II percentages similar to the control (70.29% and 75.49%, respectively). In conclusion, it is recommended the use of TCM199 medium supplemented with pFF and hormonal treatment with 10 ng EGF/ml, 10 UI hCG/ml and 10 UI eCG/ml during the first 22 h and more 22 h with 10 ng EGF/ml for the pig oocytes maturation. Butyrolactone I and cycloheximide effectively arrested/resumpted maturation; however, the oocytes percentages in metaphase II was the same for both cycloheximide and the control groups.