Uterine physiology and conceptus development in pigs

产仔物种的子宫生理学支持和适应多个胚胎在整个妊娠过程中的同时发育。在产仔的哺乳动物中，在怀孕早期需要有最少数量的发育中的胚胎，以便识别怀孕、维持黄体和产生孕酮。发育中的胚胎在植入前随子宫腔一起迁移，在产仔物种中，这种迁移在子宫腔内创造了足够的间隔，以允许多胎的发育。胎仔在子宫内的发育受多种因素的影响，包括排卵、受精率和着床率、胚胎的存活和发育、胚胎的总数和质量以及子宫容量和胎盘效率。子宫容量指的是子宫从怀孕到分娩所能携带的胚胎数量。有限的子宫容量被认为是导致仔猪出生体重降低的原因，这是由于胎盘发育受损和胚胎之间竞争加剧的结果。然而，猪子宫容量的生物学机制及其对发育中的胚胎的影响还没有完全阐明。这项拟议的研究将建立在我们最近的研究基础上，以了解母体-胚胎界面，并努力了解与子宫容量相关的生物学因素，这些因素会影响子宫内胚胎的发育，并最终影响后代的出生体重。本研究的目的是：1)通过比较不同体重表型的繁殖组织和胎儿的基因表达谱，确定与仔猪出生体重相关的生物学过程、候选基因和基因表达网络；2)通过比较不同体重表型的生殖组织和胎儿的甲基化图谱，探讨表观遗传机制在出生体重表型中的作用。这些评估将提供关于制定一个合格的概念所涉及的关键步骤的基本知识，以及对子宫环境如何影响监管过程的洞察。将进行的研究将导致识别大量候选基因和基因产物，这些基因和基因产物涉及猪的母体-胚胎相互作用，并将对基础科学、母体管理和生物技术产生影响。这一知识将有益于加拿大，因为它将用于提高经济上重要物种的繁殖效率，如猪，但也将解决母体胚胎交流如何影响人类健康的问题。

The uterine physiology of litter-bearing species supports and accommodates the simultaneous development of multiple conceptuses throughout gestation. In litter-bearing mammals, a minimum number of developing embryos need to be present early in gestation to allow for recognition of pregnancy, maintenance of the corpus lutea and production of progesterone. Developing embryos migrate with the uterine lumen prior to implantation and in litter-bearing species this migration creates adequate spacing within the uterine lumen to permit development of the multiple conceptuses. Development of a litter in utero can be influenced by several factors including ovulation, fertilization and implantation rates, conceptus survival and development, the total number and quality of the conceptuses, as well as uterine capacity and placental efficiency. Uterine capacity refers to the number of the conceptuses that a uterus can carry through gestation to parturition. Limited uterine capacity is considered to be responsible for reduced piglet birth weight as a consequence of compromised placental development and higher competition among embryos. However the biological mechanisms that underlie uterine capacity in the pig and its impacts on the developing conceptus has not been fully elucidated. The proposed research will build on our recent research to understand the maternal-embryonic interface and strives to understand the biological factors related to uterine capacity that affect conceptus development in utero and ultimately the birth weight of the progeny. The objectives of the research proposed here are to: 1) identify biological processes, candidate genes and gene expression networks involved in piglet birth weight by comparing gene expression profiles of reproductive tissues and fetuses of different weight phenotypes; 2) investigate the role of epigenetic mechanisms in the birth weight phenotypes by comparing the methylation profiles of reproductive tissues and fetuses of different weight phenotypes. These assessments will provide fundamental knowledge of the critical steps involved in the development of a competent conceptus, as well as an insight into how the uterine environment affects regulatory processes. The research to be conducted will result in the identification of a multitude of candidate genes and gene products which are involved in the maternal-conceptus interactions of the pig and that would have implications for basic science, maternal management and biotechnology. This knowledge will be beneficial to Canada as it will be used to improve the reproductive efficiency of economically important species, such as swine, but will address how maternal embryo communication can influence human health