| The technique of in vitro fertilization (IVF) has achieved lots of improvements since the birth of the world's first IVF calf in 1982. Even though, there are much different opinions towards the effects of some factors on IVF. So, it's necessary to optimize the technical system of IVF, which will not only be useful to clarify the contribution of the factors to IVF, but also be valuable to improve the efficiency IVF embryos production and to commercialize the IVF technique.The in vitro maturation/fertilization/culture system was optimized, based on achieve- ments in IVF research recent years, in order to establish an optimal technological system of IVF. The influence of glucose to fertilization and embryo development in vitro was investigated particularly.1. The effects of different protein supplements, including fetal bovine serum (FBS), newborn calf serum (NCS) and bovine serum albumin (BSA), and epidermal growth factor (EGF) on bovine oocytes maturation in vitro were investigated. The results indicated that serum had a striking promoting effect on maturation, compared with BSA, and FBS had a higher promoting effect to oocyte than NCS. The enhancement of EGF to oocyte maturation was obvious when the concentration was 20 ng/mL compared with control group and group supplemented with 10 ng/mL. But the maturation rate did not raise visibly following the increasing of EGF conecnt.2. There was an apparently difference among the individuals of bulls in terms of the rate of cleavage, 8-cell stage embryo and blastocyst after fertilization with oocytes in vitro. The cleavage rate of Bull 2 and Bull 3 were significantly higher than Bull 5 (62.3%, 67.4% and 35.8%, respectively, P<0.05). The dosage of heparin dad an obvious effect on cleavage rate after IVF, which can be obtained from the result that cleavage rate of 50 ng/mL heparin was higher than 10 ng/mL of heparin in this research (71.3%, 62.1%, P<0.05). Adding glucose to the capacitation and fertilization medium or not had no effect on IVF measured in term of cleavage rate and blastular rate.3. The blastular rate of IVF embryo was lowest among all treatments, regardless of supplying it at the beginning of embryo culture or after cultured for 48 h in glucose free medium. It indicated that glucose at 5.6 mmol/L had detrimental effects on early bovine embryonic development. When glucose at 3.0 mmol/L was contained from the beginning of embryo culture, the rate of embryo developed to 8-cell stage was reduced compared with the group of glucose free (59.8% vs. 59.3, P<0.05). But when glucose was supplied 48 h later, there was no difference in terms of the rate of embryo developed to 8-cell stage compared with glucose free group (59.8% vs. 59.3%, P>0.05). So it is suggested that the beneficial effect of glucose to embryonic development in vitro related to the developmental stage of the embryo. When supplying FBS as protein source, the blastocyst rate was not affected by the addition of 1.5 mmol/L glucose or not. But when BSA was contained as protein source, the supplement of glucose in the culture medium enhanced the blastocyst rate of IVF embryos enormously (23.1% vs. 17.3%, P<0.05). So it is concluded that the influence of glucose to embryo development depends upon the source of protein. Otherwise, the beneficial effect of FBS to embryo development can be confirmed from the fact that, when 1.5 mmol/L glucose was presence, the developmental rate of blastocyst was significantly increased in the group contained FBS compared with the group contained BSA (37.8% vs 23.1%, P<0.05).
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