Human Placental Development from Conception to Term

This overview relates to human placental development. The placenta is a complicated and highly remarkable organ and the organ with the shortest functional duration in an individual's life. Its role is to support the developing embryo/fetus in a relatively hypoxic environment. The placenta provides diverse lung, gut, liver, and renal functions to the embryo/fetus, as well as important hormonal and immunologic modulatory functions that affect the mother and fetus. In addition, it has aspects of controlled tissue invasion and superb vascular and antithrombotic functions and is an infectious disease barrier. Its development occurs in phases that need to be considered in terms of structural and morphological, biochemical, immunologic, and genetic components and changes, as it progresses from implantation through to its eventual separation and delivery from the uterus, at term. In fact, its successful growth and adaptations during these phases are critical for its, and the fetus', viability. Moreover, suboptimal matching of the fetal and maternal circulations due to maternal disease or malnutrition may lead to significant effects in either fetal growth or permanent metabolic and epigenetic changes in the developing fetus. This article while focused on placental development will also help underscore that the placenta cannot then be completely studied without reference to the associated fetus, the mother, the paternal genetic contribution, and the environment.