Role of cell surface carbohydrates on the development of mammalian embryos in vitro

体外培养的大鼠胚胎在2-细胞期的发育阻滞最近已通过从培养基中去除磷酸盐和葡萄糖而被克服。然而，问题仍然存在，早期1-细胞胚胎在体外发育到囊胚阶段的能力低于2-细胞胚胎。为了改善1-细胞胚胎的培养条件，我们首先检测了已知诱导小鼠卵母细胞体外成熟的PHA-P凝集素的作用。结果表明，PHA-P，尤其是E_4亚基能促进大鼠1-细胞胚胎体外发育，提示PHA-P的作用是特异性的，是对胚胎细胞表面糖基的修饰。此外，我们发现大鼠输卵管提取物中分子量约为70 kDa的大分子物质能够促进大鼠1-细胞胚胎向囊胚的发育。关于细胞表面碳水化合物参与小鼠桑椹胚期胚胎致密化过程的研究，发现被N-聚糖酶特异性切割的细胞表面N-连接碳水化合物参与了致密化过程。

The developmental block at the 2-cell stage in rat embryos cultured in vitro has recently been overcome by deleting phosphate and glucose from culture medium. However, the problem was still remained that early 1-cell embryos were less able to develop in vitro to the blastocyst stage than 2-cell embryos. To improve the culture conditions for the 1-cell embryos, we first examined the effect of PHA-P lectin, which is known to induce in vitro maturation of mouse oocytes. As the results, it was found that PHA-P,especially E_4 subunit promoted the developmental ability of rat 1-cell embryos to blastocysts in vitro, suggesting that the action of PHA-P is specific and a modification of cell surface carbohydrate moieties of the embryos. Furthermore, we found that development of rat 1-cell embryos to blastocysts was promoted with macromolecules in rat oviduct extracts, whose molecular mass was about 70kDa.Concerning the study on the involvement of Cell surface carbohydrates in compaction in the mouse embryos at the morula stage, it was revealed that cell surface N-linked carbohydrates that were specifically cleaved by N-glycanase participated greatly in the compaction process.