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

在我们的实验室里，我们建立了一个体外植入模型，以原代子宫器官培养为基质。在该模型中，胚胎在60分钟内附着在子宫内膜外植体上。妊娠第1 ~ 4天培养的小鼠子宫条胚胎附着率较低（0 ~ 15.0%）。但在第5 ~ 7天，附着率明显增加（66.8 ~ 74.8%）。这些水平显著高于假妊娠小鼠（0 -18.0%）和假妊娠小鼠（0 -15.0%）。结扎妊娠小鼠子宫输卵管连接处后，第5天的附着率明显高于假孕小鼠（10.0%）。未结扎子宫的附着率在第6、7天保持在较高水平（61.7 ~ 70.9%），结扎子宫的附着率为3.2 ~ 19.4。血清类固醇浓度对胚胎着床率没有影响。这些结果表明，子宫内膜容受性出现在妊娠第5天，胚胎因子参与了表面上皮的容受性获得，但胚胎与子宫内膜上皮之间的直接接触不是必需的。研究还表明，子宫内膜容受性的发生是短暂的，当胚胎-子宫内膜相互作用尚未发生时，子宫内膜容受性将在妊娠第6天丧失。因此，胚胎-子宫内膜相互作用的部分特征得以澄清。

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.