A novel, non-terminal surgical procedure to remove a single placentome from the pregnant ewe for gene expression and histological analyses was recently developed in our laboratory. This technique allows for evaluation of nutritional insults on placental development at more than one stage of gestation using a single animal. Early attempts to develop a similar technique in cattle were met with complications due to inaccessibility of the gravid uterine horn because of its location and mass. One alternative is to collect a placentome from the contralateral uterine horn; however, the question remains as to whether gene expression varies among placentomes based on location relative to the fetus. Pregnant heifers were maintained on forage during early gestation and later moved into pens with a Calan gate system (American Calan, Northwood, NH). On gestational day (GD) 158, five heifers were assigned to receive a hay-based diet formulated to meet 100% of NRC requirements, and five heifers were fed 70% of NRC requirements until necropsy on GD244. At necropsy, a single representative placentome was selected for analysis from the antimesometrial side: (1) of the gravid uterine horn central to the amnion, (2) over the allantois immediately adjacent to the amnion, (3) in the tip of the gravid uterine horn, and (4) in the tip of the contralateral uterine horn. Mean placentome weight was greater (P < 0.05) for locations central to the amnion and allantois compared to locations within the tips of the ipsilateral and contralateral horns, respectively. Gene expression for angiogenic factors (FGF2, ODC1, VEGFA, and FLT1), nutrient transporters (SLC7A1 and SLC2A1), and factors associated with hormone action (ESR1, IGF1, IGFBP3, CSH1, and PAG1) were unaffected (P > 0.05) by dietary treatment or location of the placentome. Results indicate that location of the placentome in relation to the fetus does not impact gene expression, enhancing the efficacy of nonterminal methodologies for sampling gene expression in placentomes.

中文翻译：

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技术说明：牛妊娠中胎盘位置与基因表达之间的关系。

最近在我们的实验室中开发了一种新颖的，非终端的手术方法，可以从妊娠母羊中去除单个胎盘进行基因表达和组织学分析。这项技术可以评估使用单个动物在一个以上妊娠阶段对胎盘发育的营养损害。早期尝试在牛中开发类似技术的尝试由于妊娠子宫角的位置和质量而难以接近，因此遇到了并发症。一种选择是从对侧子宫角收集胎盘。然而，关于胎盘的基因表达是否根据相对于胎儿的位置而变化的问题仍然存在。怀孕的小母牛在早期妊娠期间被饲喂草料，后来被转移到带有Calan门系统（美国Calan，Northwood，NH）的围栏中。GD）158，指定了五头小母牛接受以干草为基础的日粮，以满足100％的NRC要求，并且对五头小母牛饲喂了70％的NRC要求，直到尸检GD244。尸检时，从房室侧选择单个代表性胎盘进行分析：（1）羊膜中央的妊娠子宫角，（2）紧邻羊膜的尿囊，（3）妊娠尖端子宫角，以及（4）在对侧子宫角的尖端。与同侧角和对侧角的尖端内的位置相比，羊膜和尿囊中央位置的平均胎盘重量更大（P <0.05）。血管生成因子（FGF2，ODC1，饮食治疗或胎盘组的位置不影响VEGFA和FLT1，营养转运蛋白（SLC7A1和SLC2A1）和与激素作用相关的因子（ESR1，IGF1，IGFBP3，CSH1和PAG1）（P > 0.05）。结果表明，胎盘相对于胎儿的位置不会影响基因表达，从而增强了非终末方法在胎盘中采样基因表达的功效。