Uterine physiology and conceptus development in pigs

产仔物种的子宫生理支持和适应在整个妊娠期间多个概念的同时发展。在产崽的哺乳动物中，在妊娠早期需要有最少数量的发育胚胎，以便识别妊娠、维持黄体和产生黄体酮。发育中的胚胎在着床前随子宫腔迁移，在产仔物种中，这种迁移在子宫腔内创造了足够的空间，以允许多胎的发育。影响产仔在子宫内发育的因素包括排卵、受精和着床率、受精卵存活和发育、受精卵总数和质量以及子宫容量和胎盘效率。子宫容量是指子宫从妊娠期到分娩期间所能携带的胎儿数量。由于胎盘发育受损和胚胎间竞争加剧，子宫容量有限被认为是导致仔猪出生体重减少的原因。然而，猪子宫容量的生物学机制及其对胚胎发育的影响尚未完全阐明。

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