Bazer F W, Vallet J L, Roberts R M, Sharp D C, Thatcher W W
J Reprod Fertil. 1986 Mar;76(2):841-50. doi: 10.1530/jrf.0.0760841.
Conceptuses produce steroids, prostaglandins, proteins and possibly other unidentified agents which may play a role in the establishment and maintenance of pregnancy. A key event in this process is protection of the corpus luteum (CL) from the luteolytic activity of prostaglandin (PG) F-2 alpha of uterine origin. Oestrogens produced by the pig conceptuses between Days 11 and 16 appear to exert an antiluteolytic effect resulting in the sequestering of PGF-2 alpha within the uterine lumen. Failure of the pregnant uterus to release PGF-2 alpha in an endocrine fashion, therefore, allows for maintenance of CL function. Conceptuses of sheep and cattle produce proteins which, when introduced into the uterine lumen of nonpregnant ewes and cows, suppress the ability of oestradiol and oxytocin to stimulate uterine production of PGF-2 alpha. These conceptus secretory proteins appear to exert an antiluteolytic effect by inhibiting uterine production of luteolytic amounts of PGF-2 alpha. The horse conceptus produces both oestrogens and proteins during early pregnancy when uterine production of PGF-2 alpha is suppressed. Co-culture of horse endometrium and conceptus inhibits endometrial production of PGF-2 alpha. Conceptuses of pigs, sheep and cattle undergo elongation to achieve apposition between trophectoderm and endometrium but the horse embryo migrates rapidly and consistently throughout the uterus to achieve endometrial contact.
胚胎会产生类固醇、前列腺素、蛋白质以及可能其他未明确的物质，这些物质可能在妊娠的建立和维持过程中发挥作用。这一过程中的一个关键事件是保护黄体（CL）免受源自子宫的前列腺素（PG）F-2α的溶黄体活性影响。猪胚胎在第11天至16天产生的雌激素似乎发挥抗溶黄体作用，导致PGF-2α在子宫腔内被隔离。因此，妊娠子宫未能以内分泌方式释放PGF-2α，使得黄体功能得以维持。绵羊和牛的胚胎产生蛋白质，当将这些蛋白质引入未怀孕母羊和母牛的子宫腔时，会抑制雌二醇和催产素刺激子宫产生PGF-2α的能力。这些胚胎分泌蛋白似乎通过抑制子宫产生溶黄体量的PGF-2α来发挥抗溶黄体作用。在妊娠早期，当子宫产生PGF-2α受到抑制时，马的胚胎会同时产生雌激素和蛋白质。马子宫内膜与胚胎的共培养会抑制子宫内膜产生PGF-2α。猪、绵羊和牛的胚胎会伸长，以使滋养外胚层与子宫内膜贴合，但马的胚胎会在整个子宫内快速且持续地迁移以实现与子宫内膜接触。
