Functional and phenotypic distinction of the first two trophoblast subdivisions and identification of the border between them during early postimplantation: A prerequisite for understanding early patterning during placentogenesis

Journal Article · Mon Jan 15 04:00:00 EST 2018 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2017.12.167· OSTI ID:23127440

Nikolaou, Stavros; Hadjikypri, Xenia; Ioannou, Giasemia; Elia, Artemis; Georgiades, Pantelis ^[1]

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1. Department of Biological Sciences, University of Cyprus, University Campus, P.O. Box 20537, Nicosia, 1678 (Cyprus)

Highlights: • Unknown patterning mechanisms subdivide early trophoblast into two regions. • These are extraembryonic ectoderm (ExE) and ectoplacental cone (EPC). • Identifying ExE-EPC border/distinguishing entire ExE from EPC not addressed before. • These are prerequisites to grasping trophoblast patterning and were addressed here. • We identified ExE-EPC border and discovered unique features of entire ExE and EPC. The early stages of mouse placentogenesis (placenta formation) involve poorly understood patterning events within polar trophectoderm-derived trophoblast, the progenitor of all placental trophoblast cell types. By early postimplantation [embryonic day 5.5 (E5.5)], this patterning causes early trophoblast to become subdivided into extraembryonic ectoderm (ExE) and ectoplacental cone (EPC). A prerequisite to understanding this patterning requires knowing the location of ExE-EPC border and being able to distinguish the entire ExE from EPC at E5.5/E6.5, a time when the proamnioitic cavity within ExE is not fully established. However, these issues are unknown, as they have not been directly addressed. Here, we directly addressed these using trophoblast explant culture to functionally test for the location of ExE-EPC border, combined with phenotypic characterization of trophoblast proximal and distal to it. We show for the first time that the proximal-distal level of ExE-EPC border within E5.5/E6.5 trophoblast coincides with where Reichert's membrane (outermost basement membrane of conceptus) inserts into early trophoblast and with the proximal limit of extraembryonic visceral endoderm (primitive endoderm derivative covering part of early trophoblast). Based on these novel findings, we discovered that (a) the entire E5.5/E6.5 ExE can be distinguished from EPC because it is epithelial and specifically expresses Erf and Claudin4 and (b) at E5.5/E6.5, the entire EPC differs from ExE in that it is not epithelial and specifically expresses Snail. This work is expected to contribute to understanding the cellular and molecular basis of early trophoblast patterning during placentogenesis.

• OSTI ID: 23127440
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 1 Vol. 496; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
MICE
PLACENTA
SNAILS