How to Create an Embryo Penetration Route

Abstract

Numerous past investigations into human implantation have tended to pay attention to the mechanism of embryo adhesion to endometrial cells or embryo invasion into endometrial stromal tissue. For successful pregnancy, however, embryo penetration through the endometrial epithelial cell (EEC) sheet is also absolutely required. To improve the performance of assisted reproductive technology, implantation studies should also focus on EEC dynamics, in particular, the action of EECs during embryo penetration. Although only EEC apoptosis has been proposed as a mechanism for the formation of the embryo penetration route, we have also recently reported that characteristic EEC collective motion, regulated by the epithelial to mesenchymal transition, also plays a key role in permitting embryo penetration. We review here how EECs form embryo penetration routes in light of our findings.

Associations between metal concentrations in whole blood and placenta previa and placenta accreta: the Japan Environment and Children’s Study (JECS)

“…An internal standard (yttrium, indium, and thallium at 250 ng/g) was prepared using 0.14 M nitric acid. Blood samples (200 μL) were diluted (1:19) with the dilution solution (2% v / v butan-1-ol, 0.1% TMAH, 0.05% w / v polyoxyethlene octylphenyl ether, and 0.05% w / v H4EDTA) [10] and vortex-mixed before the inductively coupled plasma mass spectrometry (ICP-MS) analysis.…”

How Mechanical Forces Change the Human Endometrium during the Menstrual Cycle in Preparation for Embryo Implantation

“…As discussed, luminal endometrial epithelial cells loosen their cell-cell adhesion, reorganize their cytoskeleton, and shift their morphology towards a mesenchymal phenotype during the secretory phase of the menstrual cycle in order to become receptive for embryo implantation by resembling partial epithelial-to-mesenchymal transition [15,50]. In contrast, the endometrial stromal cells undergo a progesterone-dependent mesenchymalepithelial transition during decidualization [52,53].…”

“…It has been suggested that luminal and glandular endometrial epithelial cells lose polarity and convert to a more mesenchymal-like phenotype during the window of implantation [15,16]. This conversion is accompanied by fundamental changes of plasma membrane organization, which affects the membrane's overall structure and composition and has been referred to as plasma membrane transformation [16,17].…”

Implantation: Cell biology of embryo penetration route revisited

“…In their article "How to create an embryo penetration route," Uchida et al 1 However, it should be of interest to readers that this theory is not new, in contrast to the impression these authors give. This hypothesis was originally developed years ago on the basis of a comparison with certain processes in embryology, that is the so-called embryonic fusion processes.…”

“…Later on, we developed an in vitro system employing human choriocarcinoma cell spheroids 7 attaching to uterine epithelial monolayers, 8 that is the system Uchida et al are now also using. 1 Other groups have not focussed on complex changes in the epithelial programme and cell behaviour (as in EMT) but on partial aspects such as apicobasal polarity, 9 or properties of the apical plasma membrane and junctions. 10,11 Previous data from our group that may be of interest but have not 32,33 these two systems had been compared and the differences had been discussed, with a focus, for example, on junctional proteins and their association with the cytoskeleton, and on cell behaviour, as differing between vascular endothelial and uterine epithelial cells.…”