牛体外受精技术研究的现状与展望

The Current State of Bovine in Vitro Fertilization and Its Prospect

系统综述了牛体外受精技术研究的现状及存在的问题．并对今后的研究方向和前景提出了展望。牛卵母细胞可在不含血清的成熟培养液中获得受精及胚胎发育能力，促卵泡素、促黄体素及上皮细胞生长因子均对这一过程具促进作用。肝素是迄今最为有效的精子获能处理方法，但在受精过程中对精子获能起决定作用的是卵丘细胞和卵母细胞本身。提高受精质量可明显提高受精卵的胚胎发育能力。体外受精卵可通过改善培养条件或与体细胞进行复合培养发育到囊胚阶段．但后者更为稳定可靠。目前，牛卵母细胞的体外受精分裂率可达８０％，囊胚发育率达４０％左右．两枚鲜胚的移植妊娠率可达５０％～６０％．而两枚冻胚的移植妊娠率仅３０％～５０％。因此，尚需进一步提高体外受精胚胎的活力和改进胚胎的冷冻保存技术。

The current state of bovine in vitro fertilization (IVF) and the problem existed in this technique are reviewed. Meanwhile, the research direction and prospect of this technique are also presented. Bovine oocytes can acquire their competence for fertilization and embryonic development in a serum free maturation medium during the in vitro maturation (IVM),and this process can be enhanced by addition of follicle stimulating hormone, luteinizing hormone and epithelial growth factor to the maturation medium. Heparin has been the most effective capacitation treatment for bovine sperm, but the sperm capacitation during IVF is mainly dependent on cumulus cells and oocytes. Zygotes derived from IVM/IVF can be in vitro cultured (IVC) into the blastocyst stage by improving the culture condition or co-culturing them with somatic cells, but the result achieved with the co-culture system is much satisfactory. The yield of blastocysts derived from IVM/IVF/IVC is also strongly related to the quality of IVF. As to the efficiency of the current IVM/IVF/IVC system,the frequencies of oocytes cleaved and developed to blastocysts are about 80% and 40% respectively. The pregnant rate is about 50% to 60% by transferring two fresh embryos, but only 30% to 50% by transferring two frozen/thawed embryos. Therefore, the freezing technique and viability of IVF embryos are still waiting to be improved further.