Burton Graham J, Jauniaux Eric
Centre for Trophoblast Research, Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, UK.
Academic Department of Obstetrics and Gynaecology, Institute for Women's Health, University College, London, UK.
Am J Obstet Gynecol. 2015 Oct;213(4 Suppl):S6.e1, S6-8. doi: 10.1016/j.ajog.2015.07.050.
Discarded at birth, the placenta is a highly complex and fascinating organ. During the course of a pregnancy, it acts as the lungs, gut, kidneys, and liver of the fetus. The placenta also has major endocrine actions that modulate maternal physiology and metabolism and provides a safe and protective milieu in which the fetus can develop. The human placenta undergoes dramatic transformations in form and function between the first trimester, when organogenesis occurs, and the remainder of pregnancy that reflect evolutionary responses to changing oxygen concentrations in the earth's atmosphere. Recent research indicates a more interactive dialogue between the placenta and the maternal tissues than previously recognized. The endometrial glands provide histotrophic support during the first weeks of pregnancy, and the placenta appears able to stimulate its own development by up-regulating gland activity in response to endocrine signals. Extravillous trophoblast cells migrate from the placenta into the uterine wall, in which they interact with cells of the maternal innate immune system. These interactions have a physiological, rather than a classical immunological, outcome and most probably mediate remodeling of the uterine spiral arteries that supply the placenta. Furthermore, deportation of aggregates of transcriptionally active trophoblast nuclei, and the release of exosomes carrying microribonucleic acids challenge our perceptions of fetal-maternal signaling and where the placental interface actually lies. Here we reconsider definitions of the placenta in the light of these recent advances.
胎盘在出生时即被丢弃，却是一个极其复杂且引人入胜的器官。在孕期，它充当着胎儿的肺、肠道、肾脏和肝脏。胎盘还具有重要的内分泌作用，可调节母体生理和新陈代谢，并为胎儿发育提供一个安全且具保护作用的环境。在器官发生的孕早期与孕期剩余阶段之间，人类胎盘在形态和功能上会经历巨大转变，这反映了对地球大气中不断变化的氧气浓度的进化反应。最近的研究表明，胎盘与母体组织之间的对话比之前认为的更具交互性。在怀孕的最初几周，子宫内膜腺体提供组织营养支持，而且胎盘似乎能够通过响应内分泌信号上调腺体活动来刺激自身发育。绒毛外滋养层细胞从胎盘迁移至子宫壁，在那里它们与母体先天免疫系统的细胞相互作用。这些相互作用产生的是生理结果，而非经典的免疫结果，很可能介导了为胎盘供血的子宫螺旋动脉的重塑。此外，转录活跃的滋养层细胞核聚集体的排出以及携带微小核糖核酸的外泌体的释放，挑战了我们对胎儿-母体信号传导以及胎盘界面实际位置的认知。在此，我们根据这些最新进展重新审视胎盘的定义。
