Department of Animal Science, 442D Kleberg Center, 2471 TAMU, Texas A&M University, College Station, TX, 77843-2471, USA.
J Anim Sci Biotechnol. 2012 Jul 16;3(1):23. doi: 10.1186/2049-1891-3-23.
There is a dialogue between the developing conceptus (embryo-fetus and associated placental membranes) and maternal uterus which must be established during the peri-implantation period for pregnancy recognition signaling, implantation, regulation of gene expression by uterine epithelial and stromal cells, placentation and exchange of nutrients and gases. The uterus provide a microenvironment in which molecules secreted by uterine epithelia or transported into the uterine lumen represent histotroph required for growth and development of the conceptus and receptivity of the uterus to implantation. Pregnancy recognition signaling mechanisms sustain the functional lifespan of the corpora lutea (CL) which produce progesterone, the hormone of pregnancy essential for uterine functions that support implantation and placentation required for a successful outcome of pregnancy. It is within the peri-implantation period that most embryonic deaths occur due to deficiencies attributed to uterine functions or failure of the conceptus to develop appropriately, signal pregnancy recognition and/or undergo implantation and placentation. With proper placentation, the fetal fluids and fetal membranes each have unique functions to ensure hematotrophic and histotrophic nutrition in support of growth and development of the fetus. The endocrine status of the pregnant female and her nutritional status are critical for successful establishment and maintenance of pregnancy. This review addresses the complexity of key mechanisms that are characteristic of successful reproduction in sheep and pigs and gaps in knowledge that must be the subject of research in order to enhance fertility and reproductive health of livestock species.
胚胎（胚胎-胎儿和相关胎盘膜）和母体子宫之间存在着对话，这在着床期必须建立，以便妊娠识别信号、着床、调节上皮和基质细胞的基因表达、胎盘形成以及营养和气体交换。子宫提供了一个微环境，其中由子宫内膜分泌或运送到子宫腔的分子代表了胚胎生长和发育以及子宫对着床的接受所必需的组织营养。妊娠识别信号机制维持黄体（CL）的功能寿命，黄体产生孕激素，孕激素是支持着床和胎盘形成所必需的妊娠激素，对于妊娠的成功结局至关重要。正是在着床期，由于子宫功能不足或胚胎发育不当，大多数胚胎死亡，导致妊娠识别信号失败和/或着床和胎盘形成失败。随着适当的胎盘形成，胎儿液体和胎膜各有独特的功能，以确保血液营养和组织营养，支持胎儿的生长和发育。怀孕女性的内分泌状态和营养状况对成功建立和维持妊娠至关重要。本综述讨论了绵羊和猪成功繁殖的关键机制的复杂性，以及为了提高家畜的生育能力和生殖健康，必须成为研究主题的知识空白。
