Spencer T E, Forde N, Lonergan P
Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA.
Division of Reproduction and Early Development, Leeds Institute of Cardiovascular and Molecular Medicine, School of Medicine, University of Leeds, Clarendon Way, Leeds, LS2 9JT, UK.
Reprod Fertil Dev. 2016 Jan;29(1):84-100. doi: 10.1071/RD16359.
This review integrates established and new information on the factors and pathways regulating conceptus-endometrial interactions, conceptus elongation and establishment of pregnancy in sheep and cattle. Establishment of pregnancy in domestic ruminants begins at the conceptus stage (embryo or fetus and associated extra-embryonic membranes) and includes pregnancy recognition signalling, implantation and the onset of placentation. Survival and growth of the preimplantation blastocyst and elongating conceptus require embryotrophic factors (amino acids, carbohydrates, proteins, lipids and other substances) provided by the uterus. The coordinated and interactive actions of ovarian progesterone and conceptus-derived factors (interferon-τ and prostaglandins) regulate expression of elongation- and implantation-related genes in the endometrial epithelia that alter the uterine luminal milieu and affect trophectoderm proliferation, migration, attachment, differentiation and function. A comparison of sheep and cattle finds both conserved and non-conserved embryotrophic factors in the uterus; however, the overall biological pathways governing conceptus elongation and establishment of pregnancy are likely conserved. Given that most pregnancy losses in ruminants occur during the first month of pregnancy, increased knowledge is necessary to understand why and provide a basis for new strategies to improve pregnancy outcome and reproductive efficiency.
本综述整合了有关调节绵羊和牛的孕体-子宫内膜相互作用、孕体伸长及妊娠建立的因素和途径的既有信息与新信息。家畜反刍动物的妊娠建立始于孕体阶段（胚胎或胎儿以及相关的胚外膜），包括妊娠识别信号传递、着床和胎盘形成的开始。植入前囊胚和伸长的孕体的存活与生长需要子宫提供的胚胎营养因子（氨基酸、碳水化合物、蛋白质、脂质和其他物质）。卵巢孕酮和孕体衍生因子（干扰素-τ和前列腺素）的协同和相互作用调节子宫内膜上皮中与伸长和着床相关基因的表达，这些基因会改变子宫腔内环境并影响滋养外胚层的增殖、迁移、附着、分化和功能。对绵羊和牛的比较发现子宫中既有保守的也有非保守的胚胎营养因子；然而，控制孕体伸长和妊娠建立的整体生物学途径可能是保守的。鉴于反刍动物的大多数妊娠丢失发生在妊娠的第一个月，因此有必要增加相关知识以了解原因，并为改善妊娠结局和繁殖效率的新策略提供依据。
