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

在我们的实验室中，使用原代子宫器官培养物作为基质开发了用于植入的体外模型。在该模型中，胚胎在60分钟内附着到子宫内膜外植体上。从妊娠小鼠培养的第1天至第4天的胚胎附着到子宫条的百分比较低（0.0-15.0%）。但到第5 ~ 7天，附着率显著增加（66.8%~ 74.8%）。这些水平显著高于假孕小鼠（0.0-18.0%）和人绒毛膜促性腺激素给药假孕小鼠（0.0-15.0%）中观察到的水平。妊娠小鼠结扎子宫输卵管连接处后，第5天的附着率显著高于假孕小鼠（10.0%）。此外，在第6天和第7天，未结扎子宫的附着率保持在较高水平（61.7-70.9%），但未结扎子宫（3.2-19.4）。血清类固醇浓度对胚胎贴壁率无影响。这些结果提示，子宫内膜容受性在妊娠第5天即已出现，子宫内膜表面上皮细胞获得容受性可能与胚胎因素有关，但胚胎与子宫内膜上皮细胞的直接接触不是必需的。子宫内膜容受性的发生是短暂的，当胚胎-子宫内膜未发生相互作用时，子宫内膜容受性在妊娠第6天即丧失，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.