File:Extravillous trophoblast cartoon.jpg

Extravillous trophoblast (EVT)==

Invasion in first trimester human placenta. EVTs originate from cell columns of anchoring villi. During the first trimester of pregnancy, EVTs invade into the decidual interstitium (1) reaching the inner third of the myometrium, thereby anchoring the placenta to the uterus. They also follow the (2) endovascular route of invasion, plug, line and remodel spiral arteries (2, red), thus being responsible for the establishment of the maternal–fetal blood flow starting with the beginning of the second trimester. Prior to the opening of spiral arteries toward the intervillous space, maternal blood plasma is seeping through the trophoblastic plugs. Endovascular trophoblasts also reach and invade uterine veins and replace the venous endothelium (2, blue). Via the opened and dilated veins, maternal blood plasma and glandular secretion products are drained from the intervillous space into the maternal circulation. Endovascular trophoblasts invade and replace the tunica media of vessels, which in some cases leads to the fact that classification into artery or vein is no longer possible (2, red and blue). Endoglandular trophoblasts (3) are situated nearby uterine glands, replace the glandular epithelium and open the lumen of uterine glands toward the intervillous space. Scheme adapted from (Moser et al. 2015)

Reference

PMID 27774579

© The Author(s) 2016 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Fig. 8