Reproduction, genes and development group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK.
Theriogenology. 2012 Aug;78(3):670-7. doi: 10.1016/j.theriogenology.2012.03.013. Epub 2012 Apr 26.
Hyaluronic acid (HA), an important component of the extracellular matrix, plays a crucial role for cumulus cell expansion. Genes and proteins involved in HA synthesis and its receptor CD44 are expressed in cumulus oocyte complexes (COCs) in different animal species and increase during maturation. Hyaluronidase enzymes (Hyal) degrade HA into smaller biologically active HA fragments. To investigate the effects of the molecular size and concentration of HA on oocyte maturation and further embryo development, bovine oocytes were matured in vitro in the presence or absence of HA, Hyal-2 or 4-methylumbelliferone (4-MU); an HA synthesis inhibitor. The rates of oocyte nuclear maturation to metaphase II stage and development of embryos to blastocyst stage and blastocyst quality were recorded. Hyal-2 inhibited cumulus cell expansion without affecting oocyte maturation and further embryo development. Whereas, 4-MU at 1 mm reduced cumulus cell expansion, oocyte maturation rate and further embryo development; an effect which was partially abrogated by exogenous HA supplementation. These data suggest that HA production by cumulus cells during maturation is essential not only for cumulus cell expansion, but also for oocyte maturation and further embryo development. This effect is not affected by HA-degradation by Hyal-2.
透明质酸（HA）是细胞外基质的重要组成部分，对卵丘细胞扩展起着至关重要的作用。不同动物物种的卵丘卵母细胞复合物（COCs）中表达参与 HA 合成的基因和蛋白及其受体 CD44，并在成熟过程中增加。透明质酸酶（Hyal）将 HA 降解为更小的具有生物活性的 HA 片段。为了研究 HA 的分子大小和浓度对卵母细胞成熟和进一步胚胎发育的影响，牛卵母细胞在体外成熟过程中存在或不存在 HA、Hyal-2 或 4-甲基伞形酮（4-MU）；一种 HA 合成抑制剂。记录卵母细胞核成熟为中期 II 阶段和胚胎发育为囊胚阶段和囊胚质量的比率。Hyal-2 抑制卵丘细胞扩展，而不影响卵母细胞成熟和进一步胚胎发育。然而，1mM 的 4-MU 降低了卵丘细胞扩展、卵母细胞成熟率和进一步胚胎发育；这一作用被外源性 HA 补充部分阻断。这些数据表明，成熟过程中卵丘细胞产生的 HA 不仅对卵丘细胞扩展，而且对卵母细胞成熟和进一步胚胎发育都是必不可少的。这种作用不受 Hyal-2 对 HA 降解的影响。
