The biology of early pregnancy in the mare

我们的研究旨在了解在怀孕的第一个月，非常年轻的马胚胎与母马子宫内的环境之间的相互作用，在这个时候，由于我们不了解的原因，10-20%的怀孕失败了。早孕的成功和失败对所有家畜都具有基础和经济意义，但马是研究其潜在生理学的一个特别好的物种；马胚胎可以在第二到第四周内从子宫流出，而不会伤害母马，并且具有其他物种胚胎所没有的结构和功能特征。其中一个特征是胚胎产生和使用类固醇激素，我们认为这对影响其局部环境非常重要。这种“类固醇生成”和类固醇代谢正在被详细研究。另一个不寻常的特征是，在子宫内的头两周内，空心细胞球（即胚胎）从直径不到0.2毫米迅速膨胀到直径超过20毫米的时候，有一层薄而坚韧的透明囊包裹着它。在描述了胶囊的生化组成之后，我们现在想要验证我们的想法，即它对于将胎儿附着在子宫内膜（子宫内膜）上至关重要，胎盘将在子宫内膜上发育。我们认为这种粘连与胶囊中的特定糖分子和子宫内膜上的蛋白质分子有关，我们将使用最新的生化和分子技术对从怀孕母马身上收集的组织进行测试。为了发现怀孕失败时出了什么问题，我们使用了一个“妥协”怀孕的模型系统；在怀孕第二周结束时，我们用前列腺素治疗一些母马，它可以减少卵巢产生的黄体酮。尽管接受了治疗，但与未接受前列腺素治疗的“对照”母马相比，受精卵可以在子宫内再存活3-4天。正常妊娠和受损妊娠的胎儿和子宫材料的比较逐渐使我们能够确定与妊娠失败相关的蛋白质和类固醇激素活性的差异。

Our research aims at understanding the interactions of the very young equine embryo with its environment in the uterus of the mare during the first month of pregnancy, a time when 10-20% of pregnancies are lost for reasons that we don't understand. The success and failure of early pregnancy is of fundamental and economic importance in all the domestic animals but the horse is an especially good species in which to study its underlying physiology; the equine embryo can be flushed from the uterus throughout the second to fourth weeks without harming the mare and, also, has structural and functional features that are not found in the embryos of other species. One such feature is the embryo's production and use of steroid hormones that we believe to be very important in influencing its local environment. This 'steroidogenesis' and steroid metabolism is being studied in detail. Another unusual feature is a thin, tough, transparent capsule that envelops the hollow ball of cells (the conceptus) as it expands rapidly from a diameter of less that 0.2 mm to one of more than 20 mm during its first two weeks in the uterus. Having described the biochemical makeup of the capsule, we now want to test our idea that it is vital for attaching the conceptus to the lining of the uterus (the endometrium) where the placenta will later develop. We think that this adhesion involves particular sugar molecules in the capsule and protein molecules on the endometrium and will test this notion using the very latest biochemical and molecular techniques on tissues collected from pregnant mares.  In order to discover what goes wrong when pregnancy fails, we use a model system of 'compromised' pregnancy; at the end of the second week of pregnancy we treat some mares with a prostaglandin that reduces progesterone production by the ovary.  Despite the treatment, the conceptus can survive in the uterus for another 3-4 days after which it is recovered and compared with conceptuses from 'control' mares not treated with prostaglandin.  The comparisons of conceptuses and uterine materials from normal and compromised pregnancies are gradually enabling us to pinpoint the differences in proteins and steroid hormone activities that are associated with pregnancy failure.