Weitlauf H M, Kiessling A A
J Reprod Fertil Suppl. 1981;29:191-202.
Blastocysts were recovered from mice with experimentally produced delay of implantation. The dormant embryos were incubated in vitro for up to 24 h in medium containing [3H]uridine and supplemented with mouse serum or bovine serum albumin. Outgrowth of the trophoblast cells occurred in the presence of serum but not with bovine serum albumin. In contrast, the rate of incorporation of [3H]uridine into RNA by the embryos increased steadily throughout the period of incubation and was not influenced by the presence of serum. The change in incorporation of [3H]uridine was due to an increase in the overall rate of RNA synthesis and serum therefore has not effect on this aspect of embryo activation. The observation that a stimulatory serum factor is necessary for outgrowth of dormant embryos in vitro, but is not required for increased metabolic activity, indicates that these two aspects of embryo activation are regulated differently in vivo. With the assumption that trophoblast outgrowth and the changes in metabolic activity in vitro are analogous to the events that occur when embryonic diapause is terminated in vivo, it is suggested that the process of embryo activation after delayed implantation proceeds in a stepwise fashion with each phase being controlled in different ways.
从实验诱导植入延迟的小鼠中回收囊胚。将处于休眠状态的胚胎在含有[3H]尿苷并添加小鼠血清或牛血清白蛋白的培养基中体外培养长达24小时。滋养层细胞在有血清存在的情况下会生长，但在有牛血清白蛋白时则不会。相比之下，在整个培养期间，胚胎将[3H]尿苷掺入RNA的速率稳步增加，且不受血清存在的影响。[3H]尿苷掺入量的变化是由于RNA合成总体速率的增加，因此血清对胚胎激活的这一方面没有影响。有证据表明，一种刺激性血清因子对于体外休眠胚胎的生长是必需的，但对于代谢活性的增加并非必需，这表明胚胎激活的这两个方面在体内的调节方式不同。假设体外滋养层生长和代谢活性的变化类似于体内胚胎滞育终止时发生的事件，那么可以认为延迟植入后胚胎激活过程是逐步进行的，每个阶段都以不同方式受到控制。
