DEVELOPMENT OF A NEW PROGRAM OF IVF-ET BY THE USE OF NOVEL CULTURE CONDITIONS AND NEW METHOD OF EMBRYO TRANSFER

在本研究的初始阶段，超氧化物歧化酶对小鼠体外胚胎发育有促进作用。从这个简单的实验结果出发，利用小鼠胚胎培养系统测试了多种具有抗氧化活性的药剂的促进作用。经过深入的研究，我们将氧化应激的概念引入到胚胎培养中。在低氧或低光照条件下培养小鼠胚胎，可获得较高的囊胚率。在仓鼠和大鼠胚胎中也观察到这种促进作用。因此，发现新的概念适用于物种，人类胚胎培养设计在相同的条件下进行。在低光照、低氧和R-MEM培养基中培养，胚泡率高达60%，被称为对胚胎氧化应激影响最小的培养基。此前，据剑桥小组报道，人类胚胎的囊胚率约为18%。通过另一项实验，发现子宫内膜内移植小鼠胚胎对于检测胚胎活力和子宫内膜完整性是可行的。这一简单的实验结果表明，在着床过程中，滋养细胞的附着和渗透到子宫内膜间质间隙并不是着床建立所必需的。在研究结束时，发明了一种新的人胚胎移植到子宫内膜基质的模型，但该方法的应用至今尚未完成。这种方法的效果还有待评价。

At the initial phase of this investigation, promoting effects of superoxide dismutase on mouse embryo development in vitro was found. Starting from this simple experimantal results, a variety of agents which posess anti-oxidation activity were tested for the promoting effects using mouse embryo culture system. After thorough investigations, a concepts-oxidative stress- was introduced into the embryo culture. When the embryos were cultured under the low oxygen conditions or under the low illuminations, a higher blastulation rate was obtained in the mouse embryos. This promoting effect was also observed on hamster embryos as well as rats embryos. Thus the new concept was found to be applicable over species, human embryo culture was desined to carriey out under the same conditions. A remarkably higher blastulation rate of 60% was obtained when cultured under low illumination, low oxygen and R-MEM medium which had been known as the culture medium with minimum adverse effect on embryos with respect to oxidative stress. Previously, blastulation rate of human embryos was known at aroud 18% as reported by Cambridge group. By the another line of experiment, intraendometrial transfer of the mouse embryo was found to be feasible for testing embryo viability as well as endometrial integrity. This simple experimental result indicated that in the course of implantation, apposition as well as penetration of trophoblast into endometrial stromal space are not indispensable for establoshing the implantation. At the end of investigation period, a new model for tranferring the human embryos into the endometrial stroma was invented, but application of this method was not completed so far. Efficacy of this method still remains to be evaluated.