Molecular and immunological developments in placentas

Cytotrophoblasts differentiate in two directions during early placentation: syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs). STBs face maternal immune cells in placentas, and EVTs, which invade the decidua and uterine myometrium, face the cells in the uterus. This situation, in which tro-phoblasts come into contact with maternal immune cells, is known as the maternal-fetal interface. Despite fetuses and fetus-derived trophoblast cells being of the semi-allogeneic conceptus, fetuses and placentas are not rejected by the maternal immune system because of maternal-fetal tolerance. The acquired tolerance develops during normal placentation, resulting in normal fetal development in humans. In this review, we introduce placental development from the viewpoint of molecular biology. In addition, we discuss how the disruption of placental development could lead to complications in preg-nancy, such as hypertensive disorder of pregnancy, fetal growth restriction, or miscarriage. ? 2021 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

Automated summary

During early placentation, cytotrophoblasts differentiate into syncytiotrophoblasts (STBs) and extravillous trophoblasts (EVTs), interacting with maternal immune cells at the maternal-fetal interface. Maternal-fetal tolerance allows for normal fetal development despite semi-allogeneic conceptuses. Disruption in placental development can lead to pregnancy complications such as hypertensive disorder of pregnancy, fetal growth restriction, or miscarriage.