A basic study on mechanism of development of embryo-receptivity in the endometrium

在体外，以原代培养的子宫器官为基质，建立了体外着床模型。在该模型中，胚胎在60min内附着在子宫内膜上。妊娠1~4天小鼠子宫条贴壁率较低(0.0~15.0%)。但在第5~7天，附着率显著增加(66.8~74.8%)。这些水平明显高于假孕小鼠(0.0-18.0%)和人绒毛膜促性腺激素注射假孕小鼠(0.0-15.0%)。结扎妊娠小鼠子宫输卵管连接处，第5天的贴壁率显着高于假孕小鼠(10.0%)。在第6天和第7天，未结扎子宫的贴壁率保持在较高水平(61.7%~70.9%)，而结扎子宫的贴壁率(3.2%~19.4%)未见明显变化。血清类固醇浓度对胚胎贴壁率无明显影响。这些结果表明，子宫内膜容受性在妊娠第5天出现，胚胎因子(S)参与了胚胎表面上皮获得容受性的过程，但胚胎与子宫内膜上皮的直接接触并不是必需的。研究还表明，子宫内膜容受性的开始是短暂的，当胚胎-子宫内膜没有发生相互作用时，子宫内膜的容受性在妊娠第6天就会丧失，从而阐明了胚胎-子宫内膜相互作用的部分特征。

In out laboratory, an in vitro model for implantation was developed using primary uterine organ cultures as the substrate. In this model, the embryos attached to the endometrial explants within 60 min. The percentage of embryo attachment to uterine strips cultured from pregnant mice on days 1 to 4 was low(0.0-15.0%). However by days 5 to 7, the percentage of attachment increased markedly(66.8-74.8%). These levels were significantly higher than those observed for pseudopregnant(0.0-18.0%) and human chorionic gonadotropin administered pseudopregnent mice(0.0-15.0%). When utero-tubal junction was ligated in the pregnant mice the rate of attachment on day 5 was significantly higher than that of the pseudopregmant mice(10.0%). Furthermore, the rate of attachment to the unligated uterus was kept in a high level(61.7-70.9%) on days 6 and 7, but not to the uterus ligated (3.2-19.4). The concentration of serum steroids had no effects on the rate of embryos attached to the uterus. These results suggested that endometrial receptivity appears on day 5 of pregnancy and an embryonic factor(s) is involved in the aquisition of receptivity by surface epithelium, but direct contact between the embryo and the endometrial epithelium is not essential. It is also indicated that the onset of receptivity in the endometrium is transient, and when embryo-endometrial interaction have not taken place, endometrial receptivity will be lost on day 6 of pregnancy.Thus, a part of the characteristics of the embryo-endometrium interaction became clarified.