In Vitro Serum-Free Culture Of Goat Oocytes And Parthenogenetic Embryos

To evaluate the effects of serum-free culture on in vitro maturation of goat oocytes and development of parthenogenesis embryos, two experiments were designed: (1) in vitro serum-free culture of goat oocytes; (2) in vitro serum-free culture of goat parthenogenetic embryos. The aim is to establish an in vitro serum-free culture system of goat embryos for eliminating the side effect of serum on oocytes and embryos.1. 0.3%bovine serumalbumin (BSA) (m/v), 1%polyvingl alcohol(PVA) (m/v) and 1%insulin-transferrin-selenium (ITS) (v/v) were added to basic medium of oocyte maturation instead of serum, whereas 5% fetal bovine serum (FBS) was added to control. Cumulus-oocyte complexes (COCs) derived abattoir ovaries were cultured in vitro in these two media respectively. Maturation rate of PVA supplementation group (50.00%) was significantly lower than that of control (83.23%) (P<0.01), however, maturation rate of BSA group (71.19%) and ITS group (76.79%) had no difference compared to control. The matured oocytes were activated by ionomycin and 6-dimethylaminopurine (DMAP), and parthenogenetic embryos were cultured in SoFaa medium to observe the development of embryos in each group. Cleavage rates of BSA, PVA, ITS and FBS group were 61.90%, 46.97%, 79.07% and 83.58%, and blastocyst rates were 25.00%, 19.70%, 55.81% and 60.45%, respectively. The results showed that substituting PVA and BSA for FBS in basal maturation medium decreased significantly the ability of maturation and early development of embryos ( P<0.05 or P<0.01), and substituting ITS for FBS lowered the ability of maturation, but had no effect on the early development of embryos( P>0.05).2. Parthenogenetic embryos from the matured oocytes activated by ionomycin and 6-dimethylaminopurine (6-DMAP) were cultured in SoFaa medium with 1% ITS (v/v), 0.6% BSA(m/v) and 0.1% PVA(m/v), compared with 0.6%BSA(m/v)+10% FBS(v/v) as control. Cleavage rates of medium with ITS, BSA, PVA and BSA+FBS are 82.27%,75.10%,72.57% and 80.29%; while blastocyst rates are 38.76%,13.81%,7.73% and 56.82%, respectively. The result suggested that the first cleavage rate of the goat parthenogenetic embryos in SoFaa medium with ITS was not significantly different from that of parthenogenetic embryos in SoFaa medium with BSA, PVA and BSA+FBS (P>0.05), but blastocyst rate was significantly higher than that of BSA group and PVA group (P<0.01) and was significantly lower than that of BSA+FBS group (P<0.01).Conclusion:(1) Goat oocytes were well matured in OM medium with ITS, indicating that ITS can be applied to in vitro maturation of goat oocytes instead of FBS.(2) The cleavage rate of parthenogenetic embryos in SoFaa medium with ITS was higher than that of other groups (P >0.05). Therefore, it is available to use ITS instead of BSA+FBS in the culture of embryos during the first cleavage. However, as ITS can not support embryos to develop into blastocyst stage, it is necessary to find other materials together with ITS to take the place of FBS, or to discover other factors to gain the effect of serum on the development of embryos in vitro.